I think it's a fair point that the time to find the winners comes at a cost, but it's also hard to disentangle from the rotation. When starters struggle to go 5 innings, the burden on the pen compounds. This was especially bad last year with the rotation injuries, which not only meant we were on rotation option 9 so the pen was throwing a ton of innings(meaning more innings for even the known losers), but it removed some of the success stories(mainly Thompson but Leiter Jr. also) from the pen which made things even thinner.
I also think that some of this is self-imposed in a way that won't necessarily persist. In 2021 none of the biggest winners from bullpen roulette were around in 2022(Kimbrel, Chafin, Tepera). The closest was Effross, who was great in 2022 before he too was traded, and joined some of the 2022 winners in that regard(Robertson, Givens). But the sea change that's started is that starting with Effross(a nothing sidearming prospect they sold high on before his arm exploded) there's now arms with extended team control being built up. Thompson, Alzolay, maybe Assad, maybe Hughes, you add that base plus whatever is still coming from Iowa(including a bunch of velocity) to their clear ability to pick their top FA setup/closer candidates successfully(Kimbrel/Tepera, Robertson/Givens, Fulmer/Boxberger thus far) and I think the optimism is warranted.