Oh, I'd agree with that. I certainly don't want to say that 5e is a clone of 4e. Obviously there are some differences. The speeding up of combat is a massive improvement, for one thing. No, I'd agree with you.
Really? Virtually none of the 2e mechanics exist in 5e. And 3e? Seriously?
Take grappling as a perfect example. In 3e, the grapple rules are a page long and quite complicated. The 2e grappling rules had a chart. The 4e grapple rules are a paragraph and the 5e rules are virtually a cut and paste of 4e.
What 3e mechanics are ported into 5e? I suppose you could argue the sorcerer's style of casting is probably a good one. And, of course, the calculations of stats is straight from 3e. But, other than that? Action economy is completely different, most of 3e's complexity is gone, the classes have been virtually rewritten, healing works differently, and never minding the wealth by level calculations baked into the system.