I was a bit worried you are paraphrasing Rob Pike, but no, he actually agrees with that Knuth quote.
I am almost certain that people building bloated software are not willfully misunderstanding this quote; it's likely they never heard about it. Let's not ignore the relevance of this half a century old advice just because many programmers do not care about efficiency or do not understand how computers work. Premature optimization is exactly that, the fact that is premature makes it wrong, regardless if it's about GOTO statements in the 70s or a some modern equivalent where in the name of craft or fun people make their apps a lot more complex than they should be. I wouldn't be surprised if some of the brutally inefficient code you mention was so because people optimized prematurely for web-scale and their app never ever needed those abstractions and extra components. The advice applies both to hackers doing micro-optimizations and architecture astronauts dreaming too big IMHO.
No I've definitely heard plenty of people use this as some kind of inarguable excuse to not care about performance. Especially if they're writing something in Python that should really be not super slow. "It's fine! Premature optimisation and all that. We'll optimise it later."
And then of course later is too late; you can't optimise most Python.