You would find restrictions in any medium whether it is an online content site or a more traditional form. If you were to compare writing articles for online content sites to the traditional mediums of just twenty to forty years ago (such as newspapers and magazines) you'll find relatively few restrictions here.
Forty years ago an article, no matter how good the writing, might have sat at the bottom of a slush pile waiting for an editor to notice it. Even then it could easily have been discarded for myriad reasons not limited even just to the quality of the work. These online platforms allow you to post your content immediately and with very few restrictions. Some would say too few.
Of course, you can create your own platform with no restrictions at all. Blogspot, Livejournal and many other sites allow you to set up your own blog and write whatever content you want to write. Now... I have an LJ account and while I haven't found a way to monetize LJ it still gives you an unrestricted platform. Whereas HP has given me restrictions and paid me $50 for writing within those lines. I honestly can't complain.
You also have the option of creating your own domain name with your own website. The problem with this option is that it is a lot more work. And with both of these options you're still going to be limited, especially in the beginning, with getting traffic to your writing.
You have a lot of trade offs here. Is it perfect? Of course not. No writing platform is ever going to be perfect.