Votes of "common" people are literally meaningless

You mean votes of people that didn't care to be vested in the platform.
Yes, those are meaningless by design :-)

There's no such thing as bots attention.
True, you need to be noticed by someone with SP to get rewarded.
HF21 is improving that chance by bringing more incentive to those.

True, votes from bots are independent of quality because they are bought.
That is also being mitigated by upcoming EIP included in HF21.

quality is mediocre 99% of the time

Because 1% of the platform are content creators. Others are just greedy, eager to grab author rewards. HF21 makes that situation better.

Yes, Steem is an experiment, and I'm around because of curiosity too, but I disagree that it's failed. IMHO it's not. It added and still ads a lot of value to whole industry.