I don't have a tablet, and I don't understand any of this vector talk XD
So basically, I draw everything with a mouse, line by line, starting from sketch, directly in the drawing program (I personally use PS4 and GIMP, though I don't think this matters) just as I would if I had a tablet. So yeah, it can be done, with a bit of practice, though it takes a toll on your wrist.
I have a pretty good tablet, but in recent years my art style has become much simpler and so most of my work is done with a mouse (Using Inkscape - a free vector art program).
I also have some creative commons vector anime eyes here too (check my signature). It is pretty easy to adjust them and change the colors etc. Feel free to make requests if you have some.
This is the only sample of art I could find where I used a mouse from start to finish. I HAVE had to do inking with a mouse in college, but I preferred to do it on Adobe Flash (now Animate). Other than bragging rights, there really wasn't any upside to doing anything solely with a mouse.
The most high-profile artist I know who uses a mouse for most of their work is Adam Hughes, and this is only for rendering. He still scans in his artwork which is done traditionally (which is also my usual MO.)
I would still like to chime in that you should get a tablet if you plan on doing any digital art at all. I've heard many good things about Huion, which comes at a lower price point than a Wacom.
I use mouse to draw. See the first and last link in my signiature to see how 'well' that works, though I'm far from an experienced and talented artist. Patience and knowing what you can and cannot do are important, certain styles like paintly and with brush aren't that easy and you'll have to work with abolute 100% opacity brushes + cell shading lest you drive yourself insane fixing the lines afterwards. The mouse lacks the smoothness and rapid accurate brushing that drawing has and you'll probably be zoomed in close enough to see individual pixels half the time. Thus I also need some kind of model like a drawing or DesignDoll to trace over because getting correct proportions wtih the mouse is hard depending on your style. But if your style revolves around using simple (perhaps even Paint) tools and techniques like perfectly round heads and straight lines, then the mouse might even be easier on account of your clicking skills beating your touchscreen skills.
Mouse can be done, but drawing works better. If you're willing to invest and can afford the costs of a tablet. But don't get one of those tablets that allow you to sketch with a pen but expect you to look at the screen. Those things don't work intuitively, no matter what they might say in the advertisements. The only reason I can write with that junk is because I can write blindly, with drawing while watching the screen you'll need to invest a long time to convert any drawing skill you may have into drawing like that. Heck, I decided that my current mouse drawing skills would probably yield equal or better results than that junk, so it has been an unused and unrewarding dust-collector that I only use for the cell-shading which doesn't need accurate strokes.
Although, I guess the easiest way to draw would be to commission someone else to do it. If you're using mouse anyway and have the spending money, saving yourself the time and providing someone else a job would be mutually beneficial.
