I have always wondered about that.
I am new to building, so pardon my ignorance, but you are pretty sure then that putting exhaust fans in the top of a case will reduce airflow over the CPU and VRMs?
(Sorry to doubt you, just trying to get an idea if this is a universal phenomenom or limited to just particular cases or particular fan layouts).
I have not experimented with this, but logic tells us it is so.
I would first try the heavy front intake approach first.
One can always buy more fans later if it seems advisable.
There is another reasons for front intake only.
When you put a filter on the only air intake, your parts will stay cleaner.
Adding strong fans elsewhere tends to draw in unfiltered air from other case openings.
Lastly, extra fans cost$ and they add to the noise in your pc.
As to blower graphics cards, I really like them.
A GTX1080ti blower I once had was quiet and did the job..
Getting hot air out of the pc directly is a good thing.
The blower type of fan is not sufficient for current high end graphics cards so double and triple radial fans are now commonly used. Plus, they look good for marketing.
Not so good in that they put pressure on case cooling.