There's a few reason why I can understand having a surrender option in league is acceptable.
Game times are much higher compared to the other games you mentioned. OW on average takes 10-15 minutes. Heroes can be 20-30 minute games, Smite is 20-30, unsure on CS:GO but I would assume it averages 15-20 or so. League on average can take 35-50 minutes to finish. So giving the option of surrendering is pretty nice considering the games can take quite awhile, and if you know the outcome isn't favorable towards you (no late game scaling champs, enemy team has taken all of your outer turrets).
For real sports, the most comparable idea of surrender is forfeiting a match. I was a volleyball referee for 5+ years and plenty of teams would forfeit their games just to go home earlier or because they were down a player. Other sports have this option, it's just not called surrendering.
Another reason is because of the play styles. For a MOBA like HotS, there isn't any snowballing so games can still be won as long as you control objectives. There is no focus on items so the concept of "snowballing" really doesn't exist for that MOBA. League is mostly focused on snowballing via items and a bit of objective control, so when an enemy player is 10/0 or even 7/0 by 15 minutes then it's quite hard to come back from that. The other games don't exactly encourage snowballing either like league does, so being able to surrender and save yourself some time to start a new game isn't exactly bad.
Sure it sucks for your team if you have one player who wants to keep trying, or if you're the enemy team you don't get to see full build, but it's not as bad as people think. I mean, thanks to surrender we have the remake option too, which has been really handy whenever I've come across an AFK or someone who failed to connect. I'm sure people who play ranked often are happy with that change as well since it sucks losing LP because of an AFK.
It's really not that bad. Other games use it to. Good example is Destiny's PVP. There is an automatic surrender when you're team is far behind or getting slaughtered. Same if you have 2v6 because people afk or disconnect. The game will automatically surrender the game within a few minutes if you're down a little over half their points. They do a great job implementing it because it helps prevent you from being discouraged after getting your ass handed to you by the enemy with no hope of coming back.
I agree it could use some tweaking however, the surrender option is still good, and is still just an option. You don't have to surrender, but it's there just in case you want to :)
