I think there's a lot of truth in this. In reality "race every weekend" type series are mostly going to attract locals.It would be interesting to check back in a non-Fastnet year to see if this is in any way driven by boats deciding to have an "offshore" year.
Agree with those saying that there is no shortage of people with the cash to run a racing campaign. Perhaps those people are more concentrated in London that they used to be, i.e. your 1980s GP / solicitor / accountant based on the South Coast that owned a Sigma 33 doesn't own a J/109 in 2023? Or sailing has lost the social cachet that drew in the upwardly mobile Thatcher generations that watched Howard's Way and wanted to prove they had arrived?
There's also been a ton of stuff written about the appeal and growth of doublehanded sailing, and a lot of that has centred on the effort required to get, keep and organise good crew. When I think of the boats that have been long features on the Solent that I know of, they all have one thing in common - it isn't the owner doing the crew admin. One of the regulars takes that on.
I did that for 15 years, but this year I've graduated to owner....