What he said. Any pilot job which pays more than $30-50K is going to be either very competitive or a dead-end for an airline career. If CFI's could get hired at fractionals, they wouldn't bother flocking to the regionals (or the regionals would have to pay better).
Now it is possible for a regional FO to get hired at a fractional , but that's probably more of a diagonal move if you're airline bound. You would take longer to upgrade and build TPIC than just staying at the regional.
Also majors still probably have a slight preference for regional over corporate pilots (all else being equal) simply because they've demonstrated an ability to function in 121 and they know what they're getting into. Corporate pilots have some different cultural attitudes than 121 (that cuts both ways of course).
If you made a lateral move to fractionals, a major might wonder why you didn't like 121 enough to stick around and upgrade.