Oh really? I have a friend whose massively into Esports - super nerd and he has some great multi picks. You're probably right to be honest, if you arent massively into the sport and understand how teams perform, single sports bets are most likely better in the long run.
Don't get me wrong, you can still win some nice money when you win multiples and maybe betting esports is different; but I still think in the long end it is better to only bet on singles. How much multiples have you not placed, where always 1 pick (and a lot the pick would the lowest odd) fails.
I feel like it depends on the games and the odds. I mean if you are wagering on a single game and betting on the underdog and the odds are like 12.00 or something versus playing on 2-3 games for heavy favorites where the whole slip is like under 3.00 odds, then I would say you have a better chance with that multiple games. Parlay has been around for like many many years and I believe that it would definitely not be that much of a difference if you wager on a single game or a whole 15 game parlay, it all comes down to the odds.
I have done parlays on NBA before, many times, and I have probably broke even or lost a smudge whole season this year, maybe even earned a small amount I am not sure, it is definitely somewhere around where I started. I have done singles, I have done parlays, I have done many different combinations and it all comes down to luck if you ask me.