I haven't seen this video, but I have heard the argument and there is a fair bit of truth to it.
The issue is that in 5e, virtually every ability is something you get from your class and level. You gain a level, you get new abilities on a nice little schedule. You take a feat, that's what the player wanted. You gain a level in a class, it's what the player wanted. If you're playing a Battlemaster Fighter who made it to level 15 in Dungeon of the Mad Mage and you compare them to a Battlemaster Fighter who made it to level 15 in Descent to Avernus, what exactly do they do differently? The answer: Basically nothing. You picked the ancestry, you picked the background, you picked the class, you picked the feats, you picked the attributes, etc.
Compare this to, say, 1e/2e AD&D. Sure, on it's face, what every character can do comes from the class and level. Indeed, at level 1 you certainly do have identical characters. However, it doesn't take very long before your character finds meaningful magic items. Not just basic items, but one PC will get a horn of blasting while another might get boots of speed and another might get a sword of sharpness. These items significantly alter the capabilities of each PC, not just because it's the only way you gain abilities, but because the items themselves are a lot more potent. In earlier editions, your character's abilities was determined not by what you could select at the beginning of the game, but by what your individual character actually accomplished. You have the ability to knock down doors easily because you found that. You have a story behind how your PC came into possession of these fantastic abilities.
As D&D has steadily removed the potency of magic items and steadily increased the potency of class abilities, it has left characters much more uniform than they used to be. This has been a problem since 3e and the emergence of "builds", but it was somewhat mitigated by the fact that prestige classes added so many options that it kind of concealed it. Still, the very idea that you could have a character "build" before you even begin playing the game and you would have a reasonable expectation of having those exact abilities when you reached high level and nothing else of consequence is almost anathema to 20th century D&D.
In other words, it's a way to backdoor complain that in-game rewards in 5e are godawful. That magic items have been so deprecated and depowered in the name of not giving out too much power that they can feel like they're barely worth carrying with you. Like finding that +0 longsword really does feel kind of like finding a silver dagger used to. The fact that everything actually interesting is attuned means that you just don't get that many valuable items and finding new items suffers from diminishing returns. Magic item abilities, by and large, feel like bad versions of class abilities when they really ought to feel like character-defining major rewards of gameplay.
Even worse, there's no clear purpose for all this gold you're finding. You might find 10,000 gp, but once you've got full plate armor what exactly is it good for? You're not bringing hirelings. You can't buy items. There's no benefit to hoarding gold. Most PCs should retire by level 5 or 6.
Treasure rewards have kind of become the absolute worst thing imaginable: boring at best and worthless at worst.
No, I don't think so.
I think the bonus-hunting minigame was not a useful way to spend time. I think getting rid of stacking circumstantial bonuses was 100% the best addition to D&D that 5e brought. I think it's fine if certain tables want to re-introduce stacking bonuses and penalties. If that's how they want to play that's fine. However, I'm not interested in doing that anymore. All it adds is accounting, and that's not really a fun way to spend time.
Advantage/disadvantage as written is the perfect example of a "good enough" rule. Because unless you're going to allow bonuses to stack so high that bounded accuracy breaks, that's exactly what it is: good enough. It does exactly what you need: it keeps die rolls having a meaningful chance for success and meaningful chance for failure. And like 85% of the time, it's exactly what you'd get if you still used fixed bonuses.
Part of the issue is that, outside of combat, if you're getting double or triple or higher advantage your DM should stop asking you to roll. You roll dice when the outcome of an event cannot be determined otherwise. If you've got that much advantage, it's not really hard to determine anymore. Adding more die rolls to the game doesn't make it more fair. It just makes it more random, and stories aren't random. Don't ask dice to perfectly model reality because they cannot and will not. You're not only playing D&D when you're rolling dice. Put the dice down and just move on.
I'm perfectly okay with the mechanics not being perfect. I want the game to be fast to play and simple to resolve. I love that once I find one source of advantage I can stop hunting through the rules looking for more. I love that once I find one source of disadvantage I can stop hunting through the rules looking for more. That's perfect. No more, "Oh, wait, I forgot prayer. Oh, wait, I forgot I'm a dwarf. Oh wait, I forgot...." You can take that away when you pry it out of my cold, dead hands.
