When you join a channel or user group, you have to abide by their rules. Some channels don't want links of any kind, some don't want links to other groups (regardless of content). This has nothing to do with the number of users, but of course many groups use helper bots, i would as well, in fact i have a few in a private little group i made for my friends. It is possible to configure the bots to delete certain kind of messages, such as those containing images or sound, or stickers, urls, whatever.

First thing you have to do when joining, is read their rules, then wait and see if others do what you want to do. You can also ask if what you plan to do is allowed, they usually tell no need to pull the trigger.

Understand that Telegram (and other networks) are full of spammers, both automated or manned by real people. If you don't agree with their rules, simply leave. you can always start your own group and have your own rules.

There is an even nastier thing that can happen to your telegram account so be glad they kicked you before that happened. If individual people start using the report button, you will find yourself unable to use telegram for a number of hours or days (it becomes read only) and its not possible to appeal, even when unfair.

Just move along and let them be, this is a normal as internet has always been.