Either way, in the UK at least, it’s very much a minority issue - Hardly anyone is doing it as far as I know!
In most places, it is minority issue - including China.
the hobby/amateur market is still way bigger than the professional/semi professional market.
on the pro/semi pro side, you have boosters problem, you also have those kids changing rubbers every week or second week, while the "normal" kids are at a huge disadvantage that change maybe once every few months or years. Changing rubbers may not be cheating, but table tennis isn't a fair playing field no matter what angle we look at it.
And then we don't use the all the rules in the pro space for the amateur space - ie flooring, lighting, spacing, but then we here using Pro rules to some rules (but never all of it).
I think booster is something ITTF need to address in the pro space. This is the same as serving rule where everyone is trying to get that border line advantage.
This border line advantage is no different to someone having they personal chefs, or massage staff with them, or simply just an admin person booking the trips/hotel/flights - allowing the players to be worry free. These examples are things that even top 50 pros in the world don't have, but some weaker player from China for example, will have the perks due to uneven playing field.
End of the day, booster is such a small market compared to rubbers being sold and is only a problem in the pro space, especially in the top 100, where it becomes a majority.
It is against the rules, but it is not illegal - since there is no ways for ITTF to determine legality due to its own ruling that boosters is allowed if the manufacture puts its on. Using your Lance Armstrong example - it means if the hospital gave you the illegal substance, then it is legal - I mean, if it is illegal, it should be illegal for all, not just some.
Just in case you didn't know, the disassembling of the rubber at racket control after the match, cannot check for booster. It is only to check the thickness of the rubber and flatness of the blade. So ITTF has no ways to test, and then you have igor posting his hate messages so many times that OP things TTD hates boosters.... Only igor hate boosters on TTD as far as I can tell
