The browser add ons are one of the scam strategies that hackers use to steal the funds and information of people. They deploy fake addons into the marketplace so once any use installs on their computer it gives them access to steal sensitive information. some scammers also do these by developing fake mobile applications, especially in the android market in order to have access to the funds of users. I think we can all avoid this if we try to download stuffs right from the main websites instead of visiting app stores
That is why IOS marketplace is not suitable and last choice for hackers, it is hard to prove the source of program without proper knowledge. Btw, the Google play market is full of scam apps and the team has delisted many apps, web browser extensions to avoid the confusion in the future.