It's hard to scale beyond 4x CPU without transactional memory. Lock contention kills you.
Wow, so just toss those 64-core Threadrippers and EPYCs in the trash, then!
No, whether lock-contention is a problem totally depends on what you're doing!
However, if you think TSX is going to solve it, then I fear you don't understand the real problem with lock contention. The reason lock contention is so bad is that it forces costly context-switches, and TSX doesn't eliminate that.
TSX is only good for optimizing the case where the lock is available (i.e.
not in contention). That's still useful, in lock-intensive code, but not a magic bullet for solving lock contention. Interestingly enough, the most stark example I've seen is actually a PS3 emulator.
I wonder if Intel finally managed to fix TSX with Tiger Lake.
Yeah, I remember Intel making noise about it, in Haswell, and then they had to turn around and disable it. Then, it's like Skylake(?) that was supposed to finally have fixed it, but did they later have to disable that, as well?