They are way less than Android and Apple revokes the app certificate so even the downloaded ones stop to work.
Also the rare cases this happened in iOS the number of affected users were way small
This is a bad whatabotism since the scale is completely different and I really fear side loading. Specially because some developers will force users to get stuff outside the App Store putting everyone in risk.
I would pay for a good native iOS App. Memmy is nice but apps using web frameworks always have more limitations than any native one.