Webserials are fun. Sometimes when we get to the point where writing is our business, we forget to inject a little fun into the equation. I say, you must never lose it. Webserials also provide free content to your readers, supposedly regular free content, but the reality of that, as in my case, may waver. The also give you a practice ground, a story line to run absolutely amok in. You can experiment here, you can try things out and see what happens. In a never ending (or almost so) story, you can really go wild. I mean, you have all the time in the world to fix it if you find you've gone astray, right? Don't forget the skill involved in keeping a story interesting, keeping it twisting and growing and still hooking the reader over and over.
A webserial can be your training ground on all fronts. They keep you writing regularly. They may build you a few followers or fans. They can teach you to meet a deadline, keep you learning and growing your craft, and show you things about yourself and your writing you might have missed otherwise. A webserial can be a first introduction to both praise and criticism. They are your words made public, but are fluid enough to allow for some forgiveness and flexible enough to be changed in process. Let's face it, once a book is in print, you're not going to be able to fix something the readers don't care for. You cannot respond to feedback or revise an error at that point. And if you're worried about giving away one of your ideas to the world, well, pick a new one that you're not so invested in. Make it one that you don't see winning you that Hugo. Even so, if it goes well, you can always turn it into an ebook or POD later.
Serialized fiction has been around for so long. The Pulps did it. Magazines and Newspapers have ran them over the years. Now the internet has just picked up the long-standing tradition.
Why not give one a try?