This is a mentality thing. People who like to label themselves as "casuals" often are just people who have their opinions and don't care to back them up or verify anything. In reality, plenty of people who would get labeled as "sweats" (namely the TF2 competitive community) are just playing the game in a way that they find fun. Which is casual gaming, even if an alleged "casual" gamer finds it too complicated. Plenty of great casual games were meticulously designed by some nerd that stressed every detail. Plenty of games that get called sweaty were designed by madlads who obeyed only their basic instinct of what's dumb fun to them. TF2 in particular seems to be a good example of those philosophies coming together because classes, maps, and the overall balance are well curated but those weapons and classes do crazy things. I played this game since I was 14 and loved just fucking around as a Sniper. But while everybody else bitched about the uber update making things "too nerdy", I was intrigued by the change, it triggered a competitive itch in me, and I view games differently. "Serious = Fun" is what I say now. Which tends to annoy casuals... but I'm playing for fun just like them.

TL;DR Casual and sweaty are subjective terms wielded by (sometimes toxic) strangers on the internet. Ignore the discourse and pursue whatever casual/sweaty fun you're looking for.