I kind of agree, kind of disagree. I think the drastic changes made from TSR D&D to 5E are rather jarring. Though, it still feels more like TSR D&D than 3X or 4E. Sure, healing in AD&D was "downtime until the cleric could heal everyone," but that downtime was a big part of the draw...especially for people who think combat as sport is boring. It meant that instead of just endless, mindless combat you'd be forced to have downtime between fights, at least downtime between the big fights. And that was good. Now, you can just endlessly, mindlessly plow through fight after fight after fight with no end. At worst you need to stop for a guaranteed safe rest wherever you want thanks to your handy-dandy Leomund's Tiny Hut and never ever have to worry about food or water thanks to your handy-dandy six different ways to automatically secure food and water. 5E compared to AD&D is all the stuff that's not combat stripped to the bone, basically nothing to spend your gold on, and no incentive to do anything but fight your way through anything you face. Reaction rolls are gone. The concept of even being able to talk to monsters was kicked down the road until Tasha's. Morale is an optional rule tucked into the ass-end of the DMG. There's also things like save or die and level drain. Spell research and magic item crafting...and the quests that go with each. Domain-level play. Etc. And the switch from various dice and subsystems to the boringly unified mechanics of WotC is a dramatic change. So, while yes, 5E is more similar to TSR D&D than 3X or 4E, I can tell you as someone who's played AD&D for almost 40 years, the differences are big and noticeable.