I don’t know if it’s toxic so much as business as usual in any mature company. A lot of mature SV companies want to be different on this front but they just fundamentally aren’t.
I see it as the default, unless there's a strategy to do something about it.
I firmly believe any company needs to be pruning their employees on an ongoing basis - think Jack Welch's bottom 10%, or investment bank annual tidying before bonus season.
That doesn't mean employers need to be nasty about it, I think you can thank these people for their service, give them a nice severance package, a good reference letter, but you don't need to keep employing them until they reach senility and retire.