What Ethereum marketing likes to call a “global supercomputer” is slower than a 1950s computer built out of vacuum tubes, and running programs is more expensive than it was in 1955. (Programming ergonomics are also nearly punch card level.)
There are very few applications you’d actually want to execute on a platform like that. And every attempt to improve the design (including the long-promised PoS transition) is going to turn it into a centralized plutocracy.
It’s a fascinating science experiment that doesn’t have much purpose as an application environment. But because people are stubborn and the marketing was successful enough, “blockchain” is to this decade what “object-oriented” was in 1990s: a token gesture towards it will make managers and journalists happy.
They did in the 90s.
OO is now one of several styles, and we no longer have the drive for OO purity we did back then - modern languages and modern versions of languages tend to mix up paradigms and make pragmatic choices, rather than insist on OO everything being the only way.
If instead of focusing on the flaws and then writing off blockchains, you searched for solutions or for the people more intelligent than yourself working on those solutions, you may have stumbled across ingenious proposals like the TrueBit protocol which can perform efficient computation trustlessy, or its competitors like the very well known Internet Computer, which surely deserves some criticism but doesn't waiver to your simplistic, narrow, and misplaced argument.
Exhibit A, (Dec 9, 2021):
Vitalik Buterin, C. Jentzsch: Creating the World Computer - The Past, Present and Future of Ethereum - https://www.youtube.com/watch?v=IE8mV8N6cfw
Exhibit B, (Jul 30, 2015):
Ethereum: the World Computer: https://www.youtube.com/watch?v=j23HnORQXvs