The game sites offer fun and cool special events, (optional) IAP for enhancements, there is global chat (if that is something you enjoy doing), and there is guild-only chat. A big benefit of global chat is to learn about the game. Noobs flounder, and the game veterans are willing to answer questions in global chat.
Each person's char (or chars) grows at the player's pace. Some gamers are "all about it" while others are more casual. All of it is okay, as long as every guild member participates in guild growth through scheduled raids.
As the chars of each guild member grow, as the guild participates in more raids (for group growth) and campaigns (for individual growth), and as the guild members grow in number, the guild would increase in popularity and strength. It is an incentive to grow friendships within guilds, with other guilds, get to know your guildmates, communicate and chat with them, and just have a bunch of fun while playing a really cool RPG, or MMORPG as they're called.
Guilds can be designed any way the Guild Master (GM) chooses. Ranking officers can be designated, and typically with varying degrees of authority. This usually allows one officer to be online and in the guild at all times. Everyone lives life and in different time zones, so there are always guild members logged-in at different times which usually means there is always somebody, or some people, in the guild 24/7. With an ample number of Officers available, there usually is at least one of them there. Officers can let other players join the guild (if they want the player), answer questions and make decisions, start raids, and coordinate events in the absence of the GM.
Loyal guildmates and officers actively recruit members in global chat. When guilds first start, they typically accept any player who wants to join. Some stay and grow with you, and some are just checking out the game and won't stick with it. Officers monitor guild members' activity and will "boot" inactive or troublesome members. As the guild grows, newer and weaker players aren't allowed into established guilds. It does no good for the player or the guild.
When I played in guilds, we always had players from every time zone in the USA, players in Canada, South America, different areas of Asia, in Australia, the islands, and Europe- literally every continent and all over the globe. The diversity was fun and educational. We always had English-speaking people, but so many of them had a different native language. Because of that diversity and globalized guild, we gained many trusted and lasting guildmates. We were able to schedule raids at all hours around the clock. That flexibility was attractive to potential members, and the additional raids helped the guild grow stronger much more quickly.
The best part of guilds, that I found, was the forged friendships between players from around the world. The first guild I belonged to was in Book of Heroes. A handful of us were with the guild from the very beginning, until we closed it three years later to play a different game. Some of the guild members got to speak with each other over the phone and some guildmates met. (I got to meet the GM.) Something amazing happens in a tight-knit guild. When I played Book of Heroes, there were many of us that became an entourage, if you will. When we'd move on from a game, we would always join another game and create another guild we could all join. Even after approximately 5-6 years, there were still about 5-6 of us who always stuck together- no matter what. (We started at about a dozen who were thick-as-thieves.) We couldn't even imagine being in a guild unless we all were together. After changing games and/or being in a game for a while, people come and go. So new bonds with other players were created. The circle of friends is fluid. However, for our guild, there was the "core" group that always stuck together.

The guild (we always used the same guild name no matter which game we played) had it's own "Line" chat room with the guild name, too. Having the chat room was a huge help. It is where we had casual group chats and private chats with the officer team in much smoother chats and saved chats. So any time a guild member entered, at any time of their choosing, they could always catch up on guild events and guild chats since the chats weren't erased- which is what happens with the in-game guild chat. The Line app is free from both app stores and it is available around the world. Line also offers free phone calls and free video chats. Those were also great ways to get to know your guildmates if you wanted. Of course there are Forums here where a guild chat room could be designated. The out-of-game chat rooms were a huge asset if a player couldn't log-in to the game for some reason. Or if the server was shut down for an update. The guild members could still communicate in case of "emergencies" by having a separate chat room outside of the guild itself.
Since many people have been a member of RPG Insanity for a long time, I could imagine the same friendly group being in a guild together. Would you guys want to try a guild game if it's your cup-of-tea or if you're willing to try it? Guild games are RPG games. So for us, we'd still be playing our favorite genre of games.
I prefer the casual games, and I do not care for the strategic war games. (In war games, you build empires and wage war against other guilds.) Those games are very frustrating because you get wiped out and have to rebuild - repeatedly. War games can be ridiculously expensive (if you want to build an impenetrable fortress, city, castle, tower, etc). They are typically not games you and your team stick with very long. So they turn out to be a waste of money if you do invest money into IAP.
Attached are screenshots of different games I noticed in the app store. If you guys like this idea of an RPG Insanity guild, we could check out the different games to see which one we would like to play. Some games have different servers or platforms for IOS and Android. So we'd have to make sure that isn't the case. I'm sure we're not all playing on the same operating system! Lol.