Why is Vel'Koz support a thing?

Similar to support Brand or support Annie.

Vel'Koz has strong poke, high burst damage potential, high base damages, and access to crowd control. His mana costs and cooldowns are also surprisingly low.

I have played a decent amount of Vel support (albeit not recently) and his ability to pressure opponents, follow up on ganks (with cc and damage), and disengage potential makes him both a strong and safe choice. Just build your sightstone into ap/upgrade followed by more ap and you will even lot of damage late game while still having cc to peel and vision.

Admittedly 'damage' supports are out of vogue right now coming off the ardent craze and they cannot save allies with locket/targons/redemption/etc without foregoing some ap, but the advantages they bring are still really good if you are focused on burst combos or getting picks on enemies.

It always has been. Just one member of one of the kinds of supports.

Its similar to Brand Veigar or Annie support. They have one situational cc and poke damage. I guarantee 90% of them just build full AP, the rest who don't fall off and feed, because these are not supports. They're a mage with some utility. Buuuut that's just my personal stance.

Because idiots think damage dealer mages can duo bot, not realizing that building ful damage and selling their spellthief isn't how you support.

Spell thief's edge is really strong right now. It's not rare to see something like a Brand or Zyra support do the highest damage in a game.

With the recent buff to the damage support item, I'd expect to see more damage focused mages played in the bot lane as opposed to Janna, Soraka, Sona, and Lulu every game, which is how bot lane used to be.

Because Brand, Zyra, Malz and Annie don't function as Nuker Supports very well right now. But Vel and his true dmg do just fine. Also, is he free week perhaps?