I have always had a mixed experience, and I think I mostly agree with that blog post, for the most part. I know our most recent migration to Drupal 7 (still ongoing, about a year after I started working on it in my spare time; it's the most painful migration I've ever worked on, including migrations across CMS and languages...this particular site has been migrated from OpenACS->Joomla->Drupal 6, all of those jumps were faster and easier than the jump to Drupal 7).
I'm very uncomfortable with the direction of Drupal (the willingness to break backward compatibility without credible paths forward for users being the most painful for me). I've always assumed mostly it's due to my own ignorance, but this blog post confirms some of that discomfort is not just me not knowing what's going on. There's been a big move of putting things into the database that once resided in code, and this makes it really challenging to figure out how anything works. The abstraction runs really, really, deep, almost absurdly so. Trying to figure out what makes a page happen is an exercise in frustration a lot of the time, as it has pieces that are in code, pieces that are in Views, and pieces that come from other mysterious locations (there's stuff that I just assume will always remain beyond my kin).
Drupal 8 seems to be further down that path. Certainly there are improvements, but it just requires so much knowledge to even begin to work on anything in Drupal that it's incredibly frustrating for someone that dips in every week or so, to add new functionality or fix a bug on my company website.
Earlier in this migration, and at several stages along the way, I've assessed whether I could move our site to something else with less effort and end up with something nicer (both for users and to maintain). I opted not to at several points along the path, but I'm still not convinced that was a wise choice, even as close as I am now to launching a D7 version. Frankly, I dread working on the damned thing. It's just not fun.
As for github, I don't actually blame an OSS project for not wanting to move into a proprietary source hosting platform. I have uneasy feelings about my own projects being hosted there, and plan to work on a gitlab or Phabricator or something else deployment eventually, so we are not beholden to a proprietary third party (github is a great product and they seem like great people, but so was SourceForge at one time).
Anyway, if there were some other thing (I don't like using the term CMS, because people often assume I'm wanting a CMS...when "content management" is effectively 0% of my use case for Drupal) that had integrated forums, ticket tracker, shopping cart with subscriptions and licensing, and a way to manage docs, and it didn't require mountains of custom code, I would have already moved away from Drupal. I've considered building something custom with a framework, but this isn't my core competency or interest; I just want to put some pieces together and sell and support the software I do want to work on full-time.