We sure see some coincidences in the Giro quite often with a lack of action in the stage before the last big GC stage.
Alpe di Mera and Sestriere all weren't underraced. For 2023 Coe was raced as well as you can expect, and I don't think anyone had any hope for Giau action going down anyway. If the stages had been reversed in 2023 then Rog defending 11 seconds would have led to Thomas waiting for Tre Cime to attack. Big deal. 2019 didn't have a serious mountain stage before Monte Avena, 2018 had Finestre as the penultimate mountain stage, 2017 had the Piancavallo stage that almost had a Fuga Bidone, 2016 had Nibali going nuts on the Agnello. 2015 had Aru attacking quite early on Cervinia, 2014 saw pretty normal amount of action on Rifugi Panarotta a day before Grappa MTT and Zoncolan the day after that as well as pretty hard action on Montecampiones before the Val Martello
tappone. Basically your entire argument rests on Santuario del Castelmonte, which was like 6km at 7.5% coming after a 20km valley was underraced. And even there Carapaz attacked a few times. In 2011 Contador destroyed everyone with Rujano on Grossglockner the day before Zoncolan and 2 days before the biggest mountain stage of the last 15 years.
It's not really fear of fatigue that drives strategy much, it's risk/reward now versus later. When the Tour does 3 mountain stages in a row these days, nearly always will there be one that's just not a good place to attack.
I don't buy that. How is it worse than 2015 in that regard?
Isola 2000 > La Toussuire
Couillole > Alpe d'Huez
Pdb = PdB
Pla d'Adet > PSM
And I even more strongly disagree with 2019 having the worst mountain stages of the decade, judged by the route as it was intended.
I see why you'd think PdA is a better stage than PSM, but Unipuerto PSM isn't even that bad. Isola and Couillole I literally can't tell if you're taking the piss or not cause the connectivity of climbs to Isola is so much worse and Croix de Fer is much more attackable in general with a 5km 9% section near the top. Couillole is just an easier design than Telegraphe/Galbier/Alpe d'Huez in every possible way.