I've seen this argument a few times and honestly I don't get it - how do people propose we otherwise measure relative success of particular interventions -- Vibes? I've found that people who complain about how everything needs to be measured and how measurements are imperfect are often just bad at devising measurable quantities as proxies of real-world benefit. Sure it can take a bit of time to devise such measurements, and they're not inherently valuable, but if I can prove that a given variant performs better, why not pursue the preferable alternative?

It seems easy enough to say "keep the youtube we love" but how do you think this variant came about in the first place? I can assure you there have been numerous A/B tests that have led to the current feature set. And even if its a local rather than global maximum, at least there are measurable qualities by which it is preferable. Also - do you believe that everyone who says this is harkening back to the same historical reality? This is quickly approaching "make youtube great again" territory - when exactly was it great again? and why? This statement is easy to agree with and hard to prove.

It also seems easy to handle links to different variants; just supply a URL parameter. This is a non-issue.

If someone out there has a non-tea leaf divination style alternative to measuring things as a way to determine success, I'm all ears, but I don't believe in fortune tellers, and people who make software shouldn't either.

So now the average Joe has to make 3 vids instead of 1 every time - as everyone else is now min maxing their engagement?

Just sounds rubbish both for viewers (look how terrible titles and thumbnails are after a/b tests) and uploaders alike