That is actually usually not that bad (if there is, you know, revenue). What is really bad is when those teams start to roll out a lot of custom code that other teams need to use. If they are just configuring standard tools for everyone else it is usually fine (as long as they are not going to crazy with it).
The "platform" team at my company has rolled out a completely custom query language that we have had to learn and write so they don't have to make new endpoints to access different combinations of data
And they haven't documented anything
"There are integration tests, those are documentation go read those"
