The club would be killing managers careers if other clubs were not willing to give them a chance, and thats false. Other clubs did give them a chance and they also failed in those clubs, or are you suggesting that Scolari lost 7-1 because Chelsea fired him, AVB was latter fired by Spurs because Chelsea fired him before them, RDM failed in Schalke 04 and Aston Villa because of Chelsea...Mourinho was a flop with United because he was sacked in 2016?
If you think for a while you just realize the cheap narrative that Chelsea is a bad place for managers just doesn't make much sense. Do you know how many permanent managers Bayern had since 2007? 7. How many permanent managers Real Madrid had since 2007? 9. How many permanent managers Real Madrid had since 2007? 6. How many many permanent managers Chelsea had since 2007? 8. Thats not really different from the numbers from Real, Bayern and Barcelona...but nobody is saying those clubs destroy manager careers.