I think it is important to not get into a dichotomy of thinking in which you have to do either or. I think ideally someone finds whatever frequency works "best" most of the time for them (whether that is 1x, 2x, 3x, etc.), then you spend most of the year at this "best" frequency while dipping into times of less or more frequent at other times of the year as a change up/different stimulus/etc.
I think in general for natural athletes and those looking to build strength more frequent approaches work well/better and that the idea that the SBS (and other similar like minded individuals) put forth of building up to a certain volume per session, then progressing to splitting that volume over split sessions, then building up those new sessions to higher volume, then splitting it again to even more sessions as volume hits certain levels, etc. works quite well. Either doing this for a specific movement or body part, then dropping the volume back down and focusing on a new body part or movement, or just a as an overall balanced approach in this sense seems to work quite well.
Training doesn't have to always be high, low, or medium volume, you can adjust as needed and to what seems most appropriate for you and the current goals/schedule/recover-ability.
I'd caution trying to draw causation to strength stagnation for a crossfit style training approach. That is a very broad and usually not uniform term to training that could literally mean anything. Plenty of well thought out high frequency programs can balance strength and cardiovascular adaptations and improvements to a pretty strong degree (obviously probably not as much as solely focusing on one, but still allowing for quite a ton of progress).