The reason being Security.
Unfortunately, such tactics arent enough to deter cybercriminals.
There are still many malware that manages to bypass Googles security and can inject malicious web client extension.
It is also found that cybercriminals also managed to place their malicious extensions in the official Web Store.
This isnt the firstmalicious extensionthat has made it past Googles watchdogs, and its not alone in the store.
Unfortunately, however, theyre getting a lot of downloads, with a few thousands each.
source: www.techworm.net