That moment you need a messaging bus for a part of your application and there is always 1 cheeky dev who will shouts for building it oursevles instead of using of the shelve libraries.... STFU and GTFO

Why do some developers seems to be fine if you copy paste some simple code but are losing it when it comes to using new libraries/services which are designed for exactly your problem?

Commen aspects are because...

1) the documentation sucks, and figuring out how this works takes longer than coding yourself.

2) it has been coded with "works for me", and your use cases have not been tested.

3) the bugs of point 2) are hard to fix because of point 1).

4) you get another dependency that can and will break on updates.

5) it pulls in another truckload of further dependencies, all of which suffer from point 1) to point 5).