But MV3 security isn't all Google claims.
Not perfect but note
Google publishes extensions , Microsoft publishes extensions even used to authenticate into some of Microsoft if I recall correctly
Extensions I have recommended like Symantec and checkpoint are very likely used by some banks / federal agencies around the world and are actively used by top of the fortune companies
Symantec , checkpoint , bitdefender all have teams researching vulnerabilities of extensions and published research about malicious extensions and you can probably get a fat bounty of you can bypass an extension made by top security companies in the industry and used by some of the top enterprises
So although it's 100 percent true it increases attack surface
The extensions I have recommended based on objective data from debug bear of their impact on page loading, looking at ram usage in both a midrange laptops (8gb of ram ) and a low end (2gb of ram ) as well as subjective personal experience
So I have chosen based on trust (top security companies) , performance , detection in a variety of tests ( first of all openpish , pishing and those that have good results I have tested them against fake sites in artists against 419 database every couple of days , weeks in over a period of over 2 months )
So what I'm trying to focus on is actual vectors users will be faced with , having options to not slow browsing nearly at all as for example debug bear test of Microsoft defender extension is so good its basically in my opinion at margin of error territory