"It just works" with Teltonika and Glinet as well. In most of the openwrt based routers multi-wan is already enabled. It is also very easy to do with TP-Link Omada (just enable a checkbox).

So, implying that Unifi is the only company that does this in an easy way is misleading marketing.

Comparing against Mikrotik is a very low bar.

You're refuting a point he didn't make.