That would be more Google Play policy changes than Kemco.
Google Play revises their policies every 2~3 months (based on how often I receive "YOU MUST REVIEW YOUR APPS" emails...). Besides this, an app can only be updated if it supports the latest stable version of Android SDK (Android 11 since August 2021).
This means that when e.g. Android 10 changed storage access rules, Kemco would have to update their apps so it would support the new storage rules. However, in order to push this fix, they need to support the whole SDK (which means, not using compatibility mode). This means fixing all deprecation warnings, updating the package format from APK to AAB (Google Play no longer accepts APK uploads), and in some cases it might involve rewriting some components.
Now, Kemco is a publisher, not a developer. How will Kemco upgrade a whole Magitec or World Wide Software game, specially considering these studios pretty much no longer develop Android games, much less with Kemco?
So it is inevitable that as new Android versions are released and Kemco becomes unable to comply with Google Play policies, they end up with the only option of removing the app. I don't even know if Kemco ever had the source code, to begin with; Without that, even if they wished to keep the game, they wouldn't be able to.
Off-Topic: This website do have some occasional issues with mass spam. Staff has to remove spam manually, while bots post spam automatically. Once, there was more spam than staff to handle that, which is when MSG Commander deleted a few hundred of accounts, removed some less used features, etc.
It is not exactly "RPG Insanity is being abandoned", but "RPG Insanity has only so much staff, while spammers have an infinite number of spambots at their disposal, so we had to make some sacrifices as we will never have an infinite amount of staff at our disposal". I think this is what you were talking about? Excuse me if I am wrong
