YOU are what decides whether you’re hired at mainline, NOT the current company you’re employed with to build experience. Don’t listen to the negativity of others that are not successful in moving on because pilots in general are known excuse makers and rarely admit their own faults/failures when it’s easier to blame something else out of their control.
DO NOT choose a regional airline based on “career progression.” Nothing good ever comes easy and no one is entitled to be hired at mainline, despite the attitudes of many millennials we have at YX. The effort to move on needs to come from you, not from your employer.