The regular Mini-14 was not meant to be scoped. Aftermarket scope mounts flourished but all had one problem in common - the scopes would break. Even high end scopes like Leupold could not withstand the pounding they received.
Top ejection meant that the brass impacted the scope base. This energy was transferred to the scope. The violent recoil of the slide slamming back also made the receiver behave like a tuning fork, transferring the energy into the scope.
In modifying the Mini-14, Ruger did several things besides adapting the receiver for its own rings. First the side mounted ejector meant that brass would no longer slam into the scope base. Second the recoil buffer ring dampened the slide's travel back, reducing the tuning fork effect of the receiver.
Keep shooting a Ruger Mini-14 not meant for a scope and the scope will fail. If it hasn't yet, it will.
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!