It is intentional that new users are steered towards answers instead of comments. SO is a question & answers site and comments are mostly meant for clarifications, not for discussion. This is something that new users that are used to how forums work are not expecting. The hope is that by the time they have 50 reputation, they understand a bit more how comments should be used on the site.
There are additional reasons, the existing moderator tools would not be sufficient to deal with the kind of abuse that would be possible if anyone could post comments, there is simply no meaningful review of new comments on old posts.
And acquiring 50 reputation is generally not hard, that is 10 upvotes on questions, 5 upvotes on answers or 25 suggested edits that improve other posts. You could also earn 200 reputation on any other Stack Exchange site and be able to comment on all of them.
That makes sense, it would be nice if there was a linked site for discussion though. As a lurker my first instinct to dip my toes in the water is to comment on something first.
There are additional reasons, the existing moderator tools would not be sufficient to deal with the kind of abuse that would be possible if anyone could post comments, there is simply no meaningful review of new comments on old posts.
And acquiring 50 reputation is generally not hard, that is 10 upvotes on questions, 5 upvotes on answers or 25 suggested edits that improve other posts. You could also earn 200 reputation on any other Stack Exchange site and be able to comment on all of them.