hmmm . depends on the airline's perception of your previous companies 'cultures'.
A lot of airlines steer clear of experienced crew, so as they dont want to pick up crew with 'bad habits' from other carriers.
All airlines like to have clean slates to work off.... want their crew to do it their way, and not for crew to be thinking you can do it better.
Ie carrier 'A' thinks their service standards and procedures are far superior to Carrier 'B' .... therefore why would they hire carrier 'B' staff, when they are already trained in 'sub-standard' standards and procedures.
Its not reality all the time, but it is recognised it is hard to 'train-out' previous carrier experience.
Its all about company egos......that most airlines believe their staff are the best, and another carrier's staff must, therefore, be much worse ...
My spin on it anyways