Originally Posted by lee boze
I don't understand, why would the google play store be blocked?
Sometimes it is, server errors, etc. Or it has device / country restrictions, so you can't install something because you're travelling, or your carrier blocks access to certain apps, in effect blocking the store by filtering or delaying updates. Many ways in which it can be blocked.
Maybe you can't / don't want to use Google's store, but need an app.
The only solution in all these cases is to sideload an apk file directly.