you're kinda overblowing the "made for a specific player" argument. teams in tour still need to be able to cover as large a portion of the meta as possible, whilst also being good against your opponent's general "style", so to speak. those 2 aren't mutually exclusively but rather go hand in hand.
tour play is also extremely influential on ladder play, and that's simply because tour is where most of new techs or even mons will catch on. there's a TON of examples of this, but to say some of the biggest recent ones: mega alakazam, z-move heatran, sd tapu bulu, RH tornadus.
those are all pretty recent, started in tour and have cemented themselves as absolutely top of the meta in both tour & ladder. the only time where ladder will have any influence on tour is generally OLT, but even then few trends really solidify. as is evident with this OLT; the only mons that gathered real usage in OLT first and continue on an upwards trend are M-Mawile, Rotom-W & offensive Scarf Lando, whilst things like serp, gyara, HO in general obviously did not. even stall trends started in tour but caught on now.
tl;dr tour play influences ladder play and outside of OLT the reverse generally just doesn't happen.