That's orthogonal. You could always scale performance by throwing money at it in the past; the issue here is the promise of "free" performance improvements just by virtue of the natural upgrade cycle.
I believe the point of the poster you replied to was that if you have software running at speed X it won't get particularly faster if you run the same software on a 32-core CPU. Not if the original system also ran at 3.5GHz. I.e. it doesn't get magically faster by throwing more cores at it. It could get faster by better or faster caches etc, and that's valid, but the additional cores don't magically help.
If you mean that compiling gets faster.. then yes, with 'make -j' it will. But that you're compiling C++ has nothing to do with it, except that (as with most other modern languages) you have individual components which can be compiled in parallel. But this is hardly what the grandparent meant by automatically getting a speed boost just by executing existing software on a newer system.
When people talk of "Moore's law", they really imply that there's a huge class of problems that get solved automatically just because transistors get smaller and smaller.
This hasn't been true for a long while now. Yes, technology get better with time, but we don't get things like 32 cores in a PC just because transistors shrunk; smart people worked really hard to optimize this stuff.
TL;DR - there's no more free lunch in computing anymore.