Wimbledon-Putney-CJ still has a daily service
It does, but is not used these days for regular interval all day engineering blocks diversions, which is actually what was being talking about, although drifting.
Long ago Via East Putney on several Sundays a year could have 4 TPH each way diverted that way.
But nothing like that as been done for years and years now.
Certainly the last time I myself travelled on such diversions moves was in Cig type stock - so that dates it +20 years. I am pretty sure it has not been used for regular interval service diversions in the 202x years, and I'd even suggest not in the 201x years either . The District Line service these days is more intense than it used to be. The SW Windsor lines services too - which makes for more conflicting moves of Up trains over the leads at Wandsworth Town where the Up diversions have to cross both Down Windsor lines, and, all diversions traverse a single line section albeit short. Not impossible but I suggest impractical when it comes to performance risk.
Unsure on this bit - but again there is a possible train crew route knowledge issue - I know of at least one country end SWT depot that I was told by someone based there lost route knowledge on in some time ago (and why I wrote SWT there not SWR, it was lost in SWT days). Obviously quite a lot of crew must know it because of ECS movements to/from WDON, but there are only about a dozen paths in total, and even then a couple of those are Q paths it is not the big use some like to make of it.