The “or later” is optional, the FSF specifically doesn’t have the power to update the terms of every GPL-licensed software because the wrote the clause in such a way that they don’t.

If I give you software licensed under the GPL3, and a GPL3.1 comes out, it doesn’t apply to your copy of the software. Likewise the copyright holder of the work is also not forced to relicense their software under the GPL3.1. And even if they did, copies of the software distributed under the GPL3 would still be licensed under the GPL3.

The “or later” clause simply means that if I received a copy of a GPL3 software, I can redistribute it under the GPL3.1 if I so wish (where “I” in the previous sentence is everyone with a copy of the work, as the GPL gives everyone with a copy redistribution rights)

Except it is? Instead of cramming 22 new features, 198 bug fixes, and 3 usage changes in the next version, taking 24 months of dev time, one could release the next version with 1 new feature and however many bug fixes fit in the time frame, and release it in 4 to 6 weeks

At work we use lld as opposed ld. With ld, the project I work on links in 60-something seconds, with lld it links in less than 6.

Mold is faster than lld. It is absolutely worth it