i have 6000 hours about 10 year old steam, never cheated, never smurfed, i dont get super blatant cheaters on MM unless i queue with friends with low trust factor, but in LEM or higher there are enough guys who cheat and also have a lot of hours on an old steam account.
maybe they bought it, you know ppl get steam accounts and idle cs on them to sell to cheaters.
these guys are smart about using their wallhack too so they dont get banned by overwatch in between vac waves. you can easily cheat to global with wallhacks in a couple months. maybe in weeks. idk. like what is a couple euros for an account with a couple thousand hours idle in cs and level 20