Simple rules that can describe almost every situation are also rules that over-generalize characters to the detriment of options (everyone's noticing the same things, instead of perception allowing more observant characters to do what they could do), over-include the player's capabilities in place of the character's. (Players conversational skills failing to match with those of the character they intend to play), overly abstract what they describe (a monster's "power" or a character's actual abilities meaning something in adjudication but nothing consistent/concrete enough in-world), or demand a DM adjudicate without reinforcement or restriction (In the absence of rules every corner case ruling risks the danger of turning the table into a debate between PCs and the DM, inviting rapid ends and either producing embittered DMs or embittered players* - especially under the "pack it up" approach the video suggests - and helping to increase combative tables in the future.)

The games that OSR takes inspiration from did a lot right in their mortal power-level, reasonable growth, real risk of danger, and humanistic tones but if you're trying to sell me that the growth of rules that followed aren't a direct result of weaknesses in those games? I don't think we'll agree.

*The "Dorkness Rising" problem, for a slightly more light-hearted allusion.