Is there a talent-crunch in respective regional language movies?

There is no dearth of talent in cinema. Yet, why filmmakers bring non-native artists on board? Sometimes, certain roles require a non-native star but with a high stature, like Mammootty in Telugu film Yatra. But, the cons of casting non-native artists outweigh the pros. When a non-native artist is roped in, there would be a mismatch in many aspects- dubbing, lip-sync, look, etc. Like how Kangana stated she finds Tamil tough when she plays J.Jayalalitha (one who speaks chaste Tamil) in biopic Thalaivi. The singer of chart buster Samajavaragamana, Sid Sriram, from ALVP, was trolled for his flawed rendition. It is always preferable that native talents are roped in unless the situation absolutely demands.