Flowthru/flowback are actually beneficial, depending on your perspective.
I have a friend that was hired at Continental Express, prior to being renamed Expressjet, that was able to move on to Continental. Continental started to furlough so he was able to return to his last job as a ERJ captain, with seniority, then was able to go back to CAL during the recall.
Flowthru and flowbacks help and may actually help you, but you have to look at it in the "macro".
I don't care how dandy your career has been or whatever projections your requisite company is bragging about, that guy flowing back to the regional may be
you one day!