I disagree that it's too restrictive.
it's practically impossible to gain any privileges. I would post this in meta, but it requires 5 rep.
Really the only thing you can do to gain rep at first is to post answers to questions
You can do more than answer questions - you can ask them.
Five rep is gained in a single upvote on a question you ask - and asking questions is something you can do without any rep at all. The point of the requirement is to make sure that you're making some kind of positive contribution to the community before you can go about trying to change it. It's a noise filter.
Moreover, the point of the site isn't chat, comments, and such, the point is good answers to good questions. If you are asking good questions and leaving good answers, you'll be gaining rep through upvotes - 10 per answer upvote, 5 per question upvote.
I would have 5 rep, but for whatever reason it's not transferred across all stack exchange sites and remains on the Stack Overflow site where I acquired it.
If you associate your account with a 200 rep or more account on another site (which is not that hard to get if you ask/answer frequently), you gain 100 rep here automatically, enough to enter chat and leave comments. If you don't have an account with 200 rep yet, ask/answer more, you should have plenty of rep in no time!
how this is logical at all?
It's to encourage use of the site for its intended purpose. If you have the answers, you gain points and privileges by sharing them. If don't have answers and you're here to learn, then you get those through asking for explanations of what you don't understand.
The site is first and foremost a Q&A site. The other features you need rep for are extras designed to improve the Q&A aspects, so I don't see a problem with restricting them until users have demonstrated a contribution through the basics.
EDIT to address your edited-in points as well:
Also, you shouldn't have to have rep to upvote a comment. I seriously don't think you'll get spammers upvoting comments, and it's hardly hurtful.
While there probably isn't a spam problem, there definitely could be a shell-account upvoting problem, and you seriously need only 15 rep to upvote. It's not a terribly restrictive requirement, and you don't lose much by not being able to do it at the very beginning.
And how come you can only link your accounts when you have 200 rep, they should always be linked,
I'm pretty sure you can link them anytime, you just don't get the rep bonus unless you already have 200 on one site.
and until you have 200 rep, you can't post questions or answers in meta, making it literally impossible to earn points in meta
This is incorrect. It is indeed possible, and you only need 5 rep to participate in meta.