Who are you writing for? If you're writing for yourself, you can do it in a local document that guarantees it won't be shared or stumbled upon publicly. If you are dipping your toe into public writing, maybe a place like Adagia.org will work for you as you gain confidence. You've got a few thoughts and you don't mind sharing them among a group of people who reciprocate. Maybe you're here to de-sensitize yourself to a more public promotion of your work.
Are you writing here because you don't want to spend time doing research? Why don't you have your own blog? Why not maintain your own web presence? There are lots of options. There are free options that you could enjoy for free for a long time - and there are free options that may disappear. A public place like Medium might be good to gain exposure - but the tradeoff will be a user experience that declines once they host tries to find their financial footing.
Maybe you don't need to get better at writing - you just need to get paid for it. In that case, time spent here is probably not time well spent. You could make $50 / hour for your writing and instead of getting the cash and putting it into your retirement fund, you spend it here. But practice is also a great investment of time. If you're here to practice - keep showing up and putting the reps.
The choices we make include more than just the who we're writing for - it includes the opportunity cost and time value of money. When we're typing words in here, we're not doing everything else - including exercise, socializing and business building. That's the opportunity cost. The time value of money will wait for another day.