This is really a strange document...
Just a few examples:
"Don’t open emails, texts, ]...] from anyone you don’t know, don’t recognize, or weren’t expecting" <- sorry, that's not how email works. I want to get emails from strangers that care about what I do.
"Don’t use unsecure Wi-Fi networks" Largely outdated due to HTTPS and completely impractical. Everyone uses the Wifi at starbucks.
"Even better, get a VPN (virtual private network) — but, just like with antivirus software, don’t use a free VPN." How should an average user know if the VPN is a scam? (More than half of VPN providers are scam and there's little reason to believe that payed providers are always better.)
"Use tough passwords and change them frequently." Changing passwords frequently is considered deprecated advice. The single most important rule about passwords is to use unique passwords. Which they don't say at all...
I could go on...
Update: Mozilla deleted the post after criticism, see https://twitter.com/asadotzler/status/1068961020540899329