For unarmed martial arts, where some sort of keikogi is the only real equipment required, it makes little difference. Yes, a heavyweight keikogi has more impressive ‘snap’ and perhaps durability but didn’t the original Okinawan teachers just wear ordinary, everyday clothes to practise?
For armed martial arts, it does make a difference. I naturally bought cheap swords to start off with, heavy with poor balance and as a beginner it really made things difficult and it was only when trying a dojo mate’s good quality sword did I realise this. Then began the inexorable and progressive purchase of better and better swords costing me a lot of money over the years. Ironically, as one gets more experienced, crappy equipment gets easier to use.
I think this applies to all pursuits where gear is the central part of the discipline. When I started playing guitar, I bought a guitar with egg-slicer string action (that’s not good, incidentally), and a cheapo, tinny amp. Ten plus guitars later, and a lot of money, I have guitars that are effortless to play (PRS and J Custom Ibanez) which, over the years, would’ve made my learning much easier. Interestingly I bought a great amp early on (EVH 5150 original amp) and haven’t had to invest in another one.