Jason A. Donenfeld started work on Wireguard in 2016. It has since matured to the point where quite a few VPN providers offer support.
The main reason for its sudden popularity is it's unrivaled performance. Depending on your setup, Wireguard can be up to 5 times faster than OpenVPN.
The biggest down-side of Wireguard is that it requires UDP. There are situations where UDP is blocked or throttled and Wireguard is not be able to fall-back to TCP.
Some providers are refusing to offer Wireguard as it does not facilitate large-scale rollouts out of the box, requiring the provider to do additional work.
Personally, I use Wireguard whenever possible. It's by far the fastest and most reliable option I've used.