It does kind of suck that Let's Encrypt is entirely funded by donations from corporations like Google and Facebook. If they pulled support what would happen? Would 92% of websites we visit get downgraded to http?[1]

Also his point that it "supplants better solutions" is inarguably true. The 2010s had lots of conversations about certificate transparency and CA changes that just don't happen today because the existence of Let's Encrypt made it so easy to put a cert-signed website online.

[1] of US firefox users: https://letsencrypt.org/stats/