If it would be shown to give a clear significance in gaming, then I guess there should be screened for it. As it would indeed be offering an unfair advantage.
Right, in athletic sports, you're supposed to get by on training and skill. Drugs are seen as cheating. What sort of enhancements would be seen as cheating by gamers?
I'm not sure about beta blockers, but Adderall doesn't do well for games - it's more suited to holding down attention on things like spreadsheets. Modafinil doesn't work nearly as well as sleep. It helps in learning, but not so much on the battlefield, unless someone had an all nighter.
A few cups of tea might just do all of these better than drugs would. And things like L Theanine or creatine don't really need to be banned.
I agree with you, unless you have serious ADHD I don't think Adderall etc. would work very well.
I would imagine that Adderall would be useful for TRAINING for games, if you need to practice some repetitive task over and over (I'm thinking of ssbm here). Not that this warrants a ban.
There's also markets for gaming gear that has lower latency and modified gaming gear like console controllers with extra buttons or scriptable buttons.
I think the gear would give more of an advantage over drugs since it would be more consistent.
Many professional tournaments have everyone playing on the exact same hardware for this reason. You bring your keyboard/mouse and everything else is identical between competitors.