I think Marshall *could* be right about the persistent format speed problem, but it's hard to know for sure without knowing the cause. I don't know for sure if we can pinpoint design because there's a kind of self-fulfilling prophecy happening where better players seem to gravitate towards faster decks for a variety of reasons.
Something I get on the high horse about is how warping the effect the ranking system has on deck/archetype choice. People naively assume "quality of play" (.e. winrate) is the biggest (or even among the biggest) factors in determining rank, but it's probably a fair amount behind "volume of play". So if the incentives are as such that volume of play is important to your rank (even something seemingly as trivial as top 250 or even top 1200, let alone going for number 1), then "good" players (or players aspiring to that) will want to play decks that let them play more.
Another effect is that, if you accept that volume of play is an important incentive, then good/better players will prioritize faster decks absent any evidence that these types of decks are *actually* the "best" decks.
Kaldheim was an *amazing* example of this because I think multi-colored durdly snow decks were the most powerful in a vacuum. I think the sealed format and bof3 competitive environment (e.g. arena open) gave this a lot of credence. However, as players dug into the format, they found that WG and RW aggro were more likely to be open and get wins faster. So, even though multi-colored snow might have been the best in a vacuum and even diverse enough that you could almost always get the cards you needed for a good draft deck, it ended up not mattering because it was such a slow archetype. This could be happening writ large to literally every format that comes out. Point being, it's just really hard to disentangle all these effects.
One interesting data point, which is not at all conclusive, is bof3 data, which doesn't have the same rank incentives. But it's just such apples to oranges comparison, so it's nothing definitive. It just so happens this set boros is the 4th best archetype, FWIW, but, again... I'm not willing to say anything definitive, especially since you see other sets where bof1 and bof3 archetype winrates don't differ much at all.