> a removal attempt is the most effective and cost efficient way to find out whether the ting can be removed

Cost efficient for your team’s budget sure, but a 1% chance of a 10+ million dollar issue is worth significant effort. That’s the thing with enterprise systems the scale of minor blips can justify quite a bit. If 1 person operating for 3 months could figure out what something is doing there’s scales where that’s a perfectly reasonable thing to do.

Enterprise covers a while range of situations there’s a lot more billion dollar orgs than trillion dollar orgs so your mileage may very.

If there is a risk of a 10+ million dollar issue there is also some manager whose job is to overreact when they hear the announcement that someone wants to eliminate thing X, because they know that thing X is a useful part of the systems they are responsible for.

In a reasonable organization only very minor systems can be undocumented enough to fall through the cracks.