I obviously don't know what comment of mine he produced, but I'd be surprised if I said that some fans "need" isolators, because that really isn't the case. Many manufacturers say that they do, but the Wiring Regulations certainly don't, and nor is there really any 'electrical' reason.
The only real 'advantage' is that it allows to'work on' or replace the fan with the light still on - but since that is something that one usually only needs to do 'once in a blue moon' I'm not sure it really qualifies as a very strong 'advantage'