TOS is much better known than it's actually been watched.
As a result, those who haven't seen TOS take the exaggerations at face value. Those who haven't seen TOS in a very long time, have fuzzy memories and only the what stands out famously or infamously sticks out and that feeds into what others hear about it and taking that at face value. And tastes changed, so there would be fans of TNG who didn't like TOS.
All of that adds up over time. So yeah, the image of TOS and what's built up from the myth and the stories is a lot different from what I thought when I was sitting down and actually watching it.
So, I agree with the YouTube review that I saw for S2.
There are a lot of good episodes, if you take it on '60s terms. The bad episodes in S2 were the exception, not the rule.
Even the third season, I wouldn't call it a bad
season as a whole, just a mediocre season with an equal handful of good and infamously bad episodes... but I'll wait until you post your S3 review until I get into that.