That's where I disagree. "Doing nothing" and "being inactive" is the same thing to me.
Being inactive has a specific meaning in BattleMaster. If you want to communicate meaningfully with other people in BattleMaster, you're going to have to adopt the common conventions. It's like saying "I want to succeed, how do I do it?" and getting mad when people tell you how to get ahead in the game rather than how to change your duchy's allegiance.
If someone wants to have a character because he only wants to read what other people are posting, I don't care.
Nor do I. But if he gets multiple messages telling him, specifically, to do something, and he doesn't even respond, he shouldn't even be a little bit surprised when he gets banned.
You should not care about inactive players. They take nothing away from you.
That used to be mostly true. Now, it's not, because anyone inside the realm is getting their taxes in gold. This means they will not revert to the realm when they autopause.
Furthermore, you are again ignoring the difference between "not doing anything" and "inactive". If they are sitting there sending every penny to their family, that is most definitely taking something away from the realm. And just because they are not doing anything you can see does not mean they are not sending the realm's troop movements to the enemy every turn. They don't even need to be in an army to do that; they just have to look at the character list (for mobile) and the realm's region pages (for militia).