Do I really need an air conditioner filter?

Yep... "BAAAADDD" idea. Don't remove your filters, you'll gum up your equipment. Nobody's house is "lint free".

I really want the least amount of resistance in order to cool the house as fast as possible during these hot summer days. Wondering what you guys think about this, thanks.

How about OTHER sources of "resistance". Simple things like, is your condenser exposed to direct sunlight? Are the coils of both the condenser and the evaporator clean? Is your current air filter new?

The air handler is designed to work with a certain amount of resistance on the air inlet side as well as on the output side. If you would remove all resistance on the inlet side, the air handler motor could overspeed and be damaged.

Modern motor controls may limit the overspeeding risk, but most definitely in the past fan motors were burned up by overspeeding from unloading the inlet. I have been told this by an a/c tech, and 55 years ago I destroyed an expensive fan motor by running it without the loading filter on the inlet side. My landlord was not happy with me, and to this day I can hear her blistering criticism of how I treated her property.

The fact is that the loading of the ductwork on the output side is almost certainly enough loading to prevent burning up the motor even with the filters removed, but this would pressurize the ductwork beyond design limits and would cause higher air flow through the ductwork (and through the a/c coil and furnace heat exchanger) than designed.

I was naive when I moved into my first apartment with an HVAC. But the owners were also negligent and did not keep up with a maintenance schedule. I was later told that they replace the filter "once a year" but privately that it was more like "only when people ask".

What happened was the unit never had a filter installed or it had a filter and it was never replaced (I don't remember which). Because it has AC, there is a pipe to drain the water that accumulates.

Well, the pipe got clogged up with lint and other debris through regular use. And when the water had nowhere else to go, it started to pool onto the floor of the storage closet. The closet was shut and I never looked at it; until I started hearing an ominous "drip-drip-drip" sound coming from it. The water had soaked the carpet, waterlogged everything beneath, and had started to pool. Mold had also started to grow into the wall.

I've never forgotten to check the filter since.

All of the answers are to the question of whether your HVAC system needs a filter. However, that's not what the wording in the question asks:

Do my AC air intake vents really need air filters?

If you're referring to filters in the return vents, that's a different question. Just in case that's actually what you're asking, let me clarify.

The air handler should have a filter in or next to the furnace that filters all of the air as it goes in. You need that and that's the only filter you should have.

Supplemental filters are sold for the registers and/or return vents. Those are a bad idea. Best case, they're thin and not dense, and don't have much air resistance. They will degrade system performance a little but aren't likely to damage it. They will accumulate some dirt and discolor over time but don't really add any useful filtration, so they're a waste of money and your system won't be as efficient.

If you add anything to the vents that does useful filtration, those will add excessive air resistance. System efficiency will suffer and it can strain the system.

The HVAC system is designed to need only the central filter, and it should do all of the required air filtration. If the central filter is not doing an adequate job, use a filter with a higher MERV rating and/or replace it more often.