Some things that Capt Eddie touched on as well and things I have noticed myself when talking about tool size and usage ...
When working with a mini lathe, like what I own, having a really large handle is a BAD THING for trying to hollow a bowl or do end grain work on the face of a bowl, plate, or lid. You have the handle of the tool held nearly parallel to the lathe ways, with the end of the handle hitting your tailstock. Very impractical.
On the other hand, I happen to have some wood-handled old-timer type flat tip screwdrivers with the square shanks that I bought for a buck apiece at a local pawn shop. I used my 1x30 belt sander to grind away the screwdriver ends and then profile them into various detailing tips. One for flattening, with a squared scraper edge, one for parting, with a very sharp thin knife edge. One for profiling, with a curved rounded scraper edge. And finally, one for chamfering and edging, with a 45 degree scraper edge. The entire tool is only 5 inches long, including the handle length. These let me get right into the bowl or box I am working on without having to remove my tailstock from the lathe. They are also small enough I can work around my tailstock with them, while hollowing small things.
Small tools, though, have a significant drawback compared to large tools. A small tool is much more prone to vibration and loss of control. You will have considerably more chatter and a more uneven surface with the small tool unless you have it VERY firmly gripped, which can lead to hand and wrist fatigue while working.
Large tools, conversely, will generally give you a farm smoother cut, as they are much less prone to vibration and chatter, being that their mass keeps them from wanting to move, leaving the tool's edge in contact with your work and moving around far less. You can use a much less firm grip, though you still have to keep it steady and let the tool do the work. Also, with the longer tool handle, you have far more leverage control and precision control of exactly where the tip of your tool is going and how fast, while with a smaller tool, it's nowhere near as precise without a huge amount of experience and a large portion of your strength and attention.
In any case, the argument for tiny carbide cutters in machine tools are based on the fact that carbide materials for those bits can be pretty expensive, in some cases ridiculously so. They still mate those tiny cutters up with some beefy and heavy tools that have a lot of mass or are fixed to something on the table or lathe bed, so as to reduce vibration to a minimum for a perfect cutting curve while hollowing your blank.
A smaller cutter CAN be more aggressive than a larger cutter, allowing you to push deeper per pass across the material than when using a larger cutting bit without stalling the work on the lathe. This is because the smaller cutter is removing less material than the larger one, even when taking a "bigger" bite. High speed turning/roughing is the key to how it works, in practice, though with even higher speeds than that the larger cutter would perform just as well.
By the exact same token, when making finishing cuts .... a larger cutter will cut across more surface area, helping to even out the cuts and give you a better surface finish than the smaller cutter, which will tend to want to dig into it.
To summarize it all up: Your tool's size of handle, weight, and cutting surfaces are all different aspects of the tools that you can change or pick from to determine the cutting performance and results you are after.
Carbide or HSS steel (or even mild tool steel, in my case of the screwdriver handles), all can be sharpened to some extent and used in different ways.
Your tool's handle can provide great leverage or excellent flexibility in use without getting in your way, depending on it's length.
Your tool's handle can provide the lightness you need to be able to maneuver it as you desire or the weight you need to provide you with a good quality cut surface.
Once you find the balance between these different aspects of your tools, you will finally start the process of mastering their use.
