Developer here. Actually I have the same Problem. I work full remote and most conversations happen via Chat. It saved me a ton of time to be able to copy important conversations into Obsidian. Now I have to summarize discussions and hope not to forget important details. (It's always the missing details that F you up the most later)
Use case
When stuff gets postponed and I have to continue working on it weeks later the interface of teams is simply not powerful enough to figure out what was discussed when about which topic. I might have had several different conversations with different people concerning a particular Task. But Teams only gives me a continuous log of one person at a time, with all sorts of other Topics in between what I am looking for. It also does not work offline. So when traveling I can't even reference it. Yes even in 2025 Germany still has no good mobile data coverage. So unless something major happens on that front, the copy and paste was the way to go. Can't understand why they needlessly disabled that. It makes live so much harder.
If there is no change here soon, we will for the development Team, spin up our own jabber instance instead. There we can decide what happens and what not.