I'd not argue this either with a traditional HVAC system.
My "understanding" (limited) is that these ductless inverter-type systems are efficient at partial loads and installing more BTUs is "more OK" than a traditional HVAC system that is too big and will short-cycle and not remove humidity?
(This is a question, not an assertion)
it's important to look at the min/max capacity of the minisplit. a house split system typically has one capacity, which is whatever it's nameplate says + the derating based on outdoor temp. a minisplit with a 12k head may have an actual capacity range from 3k-16k. at work the contractors like to oversize, so I ask for spec sheets. I'm very happy with the cooling & humidity management of a 1 ton system at low average loads.
say it's cold out and you have a 48k VS unit in your garage and it's set at 50F. you walk in and turn it up to 72F. it'll kick up from whatever capacity it took to hold 50F to warm you up to 72F - probably 100% nameplate capacity or maybe more, based on whatever proprietary algorithms the mfg chose and actual capacity of the unit (often more than nameplate). once it gets close to 72F, say 70F, 71F, it'll start dialing back the capacity to a maintenance level.
this is not how a "normal" oversized system behaves. if you have an 80k BTU single stage mr heater in your garage, it'll burn at 80k until it shuts off, then short cycle on/off while the objects (cars, tools, walls, etc) slowly **** up heat from the air.
It's always worth looking at that minimum capacity. Often, multi head units will have a higher minimum total capacity than a single headed unit. I assume this is related to oil return, but don't quote me on the reasoning.
also note that minisplits often have a "dehumidify" mode, that AFAIK targets a coil temp and slows the fan down to maximize latent heat capacity without freezing up the evaporator.
