Is capitalism exploitative

Nothing is wrong with having that motive. The motive should not contribute to the creation of poor quality threads that are essentially just polls. 

Polls? You are underestimating the ability of elevating a discussion among Dart users.

They can make civil discussions out of anything...unless somebody uncivil steps in and engages. When that uncivil person leaves it is back to civil discussions and certainly not just "polls".

We've had, at least until the advent of the Internet, a reasonable control against monopolies by law. Companies still try to engage it, but have been adequately managed to prevent them getting out of hand. Because of the nature of cyberspace, it's not as easy with internet companies, particularly when they band together with an agenda having nothing to do with the Internet business, per se, but the agenda does currently control it to prevent the free-flow of information, and that, curiously, goes against the very nature of why the Internet was created in the first place. Yes, more needs to be done legislatively to prohibit companies from taking that control, short of protection of intellectual property.

Couldn't have said it bettery myself.

Capitalism is exploitative by design.your profit is equal to the difference between wealth generated by your workers and the wages you pay them. You must exploit your workforce in order to generate profits. This is capitalism at its most basic. No economist would argue against this basic principal.