Default allow is much better suited to the average user.
Know what else is better suited to the average user?
Malware. FGAV, heuristics, etc. have failed. In
epic fashion. They can't keep up with millions of new samples every day. If they could, then drug trafficking would still be the world's #1 largest criminal industry. But it's not; it was surpassed by cybercrime in 2004.
Millions of Americans become victims of identify theft every year. Hospitals pay hefty ransoms, hoping the ransomware authors will be merciful. The bad guys are large and in charge. Meanwhile, proponents of default allow methods keep recommending discipline to Internet users. Install your traditional three-pronged security suite, keep all your software up to date, avoid opening emails from unknown senders, scan unknown files at VT, stay away from dodgy websites, etc., etc., etc.
None of this discipline will protect you when a legitimate website like NFL.com or other gets compromised, and drops a 0-day meltdown/spectre exploit on your machine. It would be more effective to discipline them to properly use something that actually works, by stopping the code
before it executes and unleashes its payload.
BTW, it doesn't have to be one or the other. Keep your antivirus if you choose; VT has a 128 MB file size limit anyway, last I checked. But don't just flat-out tell people
not to use a program that stopped WannyCry dead it its tracks, even on outdated computers.
Twenty years from now, average users will be more than capable of properly using something like AppGuard. Until then, I'll leave the light on for them here in Utopia.