Isn't the TBO for turbine engines judged partly on cycles - i.e. takeoffs and landings. The reasoning presumably being that a period at 100% power counts for more wear and tear than the same period in the cruise.
Likewise, you could argue that taxiing for long periods is bad for plugs so you should be doing 50 hour checks more often.
It seems to me that ideally in this day and age we'd have better means of judging the TBO than mere hours flown. e.g. as someone who rents by the hour it's in my interest (short of engine failure) to choose a high cruising speed and thrash the engine and burn more fuel because it's cheaper for me that way. For an owner it would be considerably cheaper to fly a bit slower, be kinder to the engine and get more flying for the same fuel.