You are definitely missing a lot. I don't think many of these would show up under "good podcasts":
Sample, for example:
* Re:Sound (curated aggregator of best episodes)
* SpeakUp (storytelling and teaching storytelling intermixed)
* Confabulation (storytelling, Canadian)
* The Moth (storytelling, worldwide)
* Story Collider (storytelling, Science topics, somewhat uneven)
* Snap Judgment (storytelling, backed by music)
* The truth (mini-stories)
* Everything is alive ("objects" talk)
* Proof (food mini-episodes)
* The Allusionist (stories about language)
* Uncover (radio style journalism. NXIVM series was great)
* Hit Parade (stories about music/trends)
And that's just the vanilla general podcasts. Then, many niches you want to dive in have their own constellations of podcasts in different levels of quality/style.
For example
* for DnD/Role Playing:
-- Critical Role (live DnD game with (niche-)famous Voice Actors), also
-- Session Zero
-- Character Creation Cast
-- Hello from the Magic Tavern
* For Impov:
-- Improv London Podcast
-- Improv Nerd
-- Improv for humans
-- Improv beat by beat
I was already listening to the podcasts before that name existed (Gilmore Gang!) I welcomed, used, and said goodbye to ITConversations. Things they did with AWS to insert new adds into old episodes were super cool for the time :-) Same with Java Posse (oh those hats!)
Just because some podcasts are now popular and tuned for the general audience does not mean that there is no longer something for those with interest for audio consumption and much more niche interests. In fact, it is the opposite, as the software becomes easier and hosting cheaper.