The internet is basically a loosely associated group of playgrounds.
Every playground has its own rules, an owner, and a set of things you're allowed to do.
Twitter let's you share content, but no more than 140 characters at a time. Medium allows you to write long-form articles, but you have to abide by their formatting and they're posted in their ecosystem.
In order to play in someone's playground you have to give them some of your power and energy. A bit of you now exists in a place where you don't have full control. Maybe it's agreeing that they can use anything you post in their own advertising (like Facebook). Maybe it's that your content can only exist in their system (like Instagram). Maybe in order to add something, you need to follow a strict set of rules (like Kickstarter).
Sometimes the playground's owner takes their bouncy ball in the middle of a game and goes home forever (like Del.ico.us, Ping, Digg, Friendster, MySpace - they all closed shop and you can't play there anymore).
There are pro's to playing in other people's playgrounds. Sometimes you can get more traction for what you create, sometimes they'll do a bit of promotion for you, and sometimes you can even become the star of the playground (like when folks get famous on YouTube).
But the problem, or downside, is always the same: it's not your playground and not your rules. They could always take their bouncy ball and go home in the middle of a game. You (and your revenue stream) could be banned from the jungle gym or monkey bars quickly, with anything from a terms and conditions update to a change in their revenue model (which excludes you making money).
Yet many people think the benefits of being on someone else's playground are greater than they are.
I've heard 100's of times that folks believe simply starting a Kickstarter campaign will somehow awaken a massive marketing machine to catapult their campaign to stretch goals (when a campaign passes its initial goal). Or that simply writing on Medium.com will bring them 1,000's of new and adoring fans. When in reality, you only get out of a playground what you bring to it. And, like Facebook, they could start charging you to interact with the audience you've built and fostered.
Even writing guest articles (and yes, there are massive benefits) comes with limitations--the CTA at the bottom of each is probably to hook up with their social media accounts or sign up for their newsletter or buy their product.
I'm not saying we should keep our own bouncy balls and focus solely on building our own playgrounds. But I am saying there are inherent dangers in solely existing and building traction in someone else's.
Existing in or building your audience in someone else's playground should never be your primary strategy.
The internet lets you easily (and cheaply) make your own playgrounds. Mailing lists cost nothing to start (and scale as your audience scales) - MailChimp's free for the first 2,000 subscribers. And a website costs next nothing to start - and allows you to use your own domain and hosting.
This way, you get to make your own rules. You get to decide who plays with your bouncy ball (your audience, your rat people) and who doesn't (trolls and people that aren't a good fit). This way, you get to keep your power and energy for yourself. This way, no one is the gatekeeper to your ideas or, more importantly, your audience.
Sure, you can play in other playgrounds. But always make sure you give clear directions with how to get to your own by linking to your newsletter and website when you guest post or add articles to content sites and that sort of thing.
The allure of other playgrounds, that already have lots of people using their jungle gym and interacting, is great. It's hard (and far less fun) to play with your bouncy ball all by yourself. But if you want to ensure you've always got access to a bouncy ball and some killer monkey bars, you've got to be the one who owns them.
So, build your own playground. Make the best jungle gym ever. Fill the whole thing with the bounciest of balls. You have the ability to do so. Ensure that others will want to play by providing them with a ton of what they are eager for.