Again, I go back to my point about doctrine and training. The UK stopped training to operate the Harrier GR7/9 under austere conditions (ie dispersed ops away from traditional airfields) in the mid-90s. AFAIK, they've never tried to operate the F-35 under austere conditions.
The USMC has done some trials operating the F-35 from a disused highway but I think they're still a long way from being able to do that operationally for an extended period.
I'll believe the propaganda about the F-35 fighting from austere environments when I actually see consistent, realistic training by either military. Talking about it is one thing. Doing it consistently and effectively is entirely different. If you're not training to do it today, then you either won't do it during conflict…or you'll apply the "learn as you go" principle which could lead to all sorts of logistical, personnel, and technical problems.
Also, it's worth noting that carrier-capable aircraft can be flown from traditional airfields. The EA-18G fleet includes dedicated "concrete squadrons" (officially they're "expeditionary") that are not carrier-qualified.
If the UK and USMC are serious about STOVL as a means of delivering survivable air power, then they need to train for it…and train hard. In the good old days of the Cd War, the Harriers worked up to completing full TACEVALs while operating from dispersed hides off-base. We need to be able to do that with F-35 to demonstrate it's a real capability rather than just a romantic pipe-dream.