I worry that a group like that would be similar to groups that allow users to post any adopts they are trying to sell. It will be filled with people offering, but little to no one is buying. --- Of course it is a good idea in that it makes a nice singular* location to browse available art trades spanning across different abilities, levels, prices, and subject matters. But I fear the supply might be higher than the demand, causing the group to be filled with a seemingly endless supply of people offering and only the newest submissions actually being viewed. Not to mention the issue of sorting them between permanently open and closed. Because you cannot rely on the user to remove the offer if it is no longer available. Plus I feel the majority of people might be more willing to do art trades with users they know and trust, and they don't need a group to do that.
Again it is a wonderland for a user looking to commission a new artist and are willing to sort through all the different folders of a group ( which is more easy than doing it themselves ), but I don't think there are many users who are going to do that. Not to mention the group would need to have notoriety and reach so people know to come there as a source for both posting and seeking. --- I'm not trying to deflate the idea but I personally think is is more work than what its worth. --- singular* Unless there are multiple groups doing the same thing, and then they have to check out each group for offers that are in one but not the other.
You can always earn points even if you are younger than 15. You could do adoptables for a low amount of points and post them to many adoptable groups. That needs a lot of work tho. If you want something, you need to work hard to get it. You can also check out if adoptables is too much work for you (but seriously.. if one is too lazy to work for points they don´t deserve them in my opinion).
Also if you think you can not draw, why would other people want to trade with you? If someone offers an quality art work they want a good quality in return of course. And if you speak bad about your own art.. I don´t know. Not a good way to represent you when it comes to trades.