Interesting trend I'm noticing.

When I look for a game mainly 5e I noticed a lot of the games only allow humans,elves, and dwarves and nothing else. Any ideas why or how this started?

Hmm. Could it be confirmation bias? (i.e. you noticed it on a couple of random games, and now it sticks out?) I just checked out the first 20 hits on a 5e game and didn't find any restrictions like that.

It seems to come in waves, I don't check everyday more like once or twice a week. And you only looked at the first 20 without even looking at the lfg forum either...also didn't say it was all games but there is a quite lot.

Probably the GM is wanting to create a world that reminds them of Tolkien's Lord of the Rings.  Not so many Dragonborn and Tieflings about there. =D

I only speak for myself - but in my games, I do not allow Dragonborns, Half-orcs & Tieflings. I run a forgotton realm setting using a lot of the known lore. Usually those 3 races has a lot of issues with society. Half-orcs are on a case by case basis but they are looked down upon by society. Tiefling are even worse and dragonborns will scare most npc and are extremely rare. I will allow them if they party agrees the troublesome that they bring in a social setting & rolling "persuasion" won't help them. 

I guess (though the forgotten realms wiki says otherwise). Just sounds more like you just don't want those races in your game imo.

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