Does an entrepreneur really need to rely on incubator for angel or venture funding?

Does an entrepreneur really need to rely on incubator for angel or venture funding?
I feel if an entrepreneur is already confident of a business and has sound business plan, should be given angel investment without going through accelerator. Please give feedback.

No, it is not necessary at all to go through an incubator to find a VC or an Angel investor. It's just one of the ways (and even a less frequent one).

In short: there are advantages. The startup get more publicity and the investor knows, that the risk is smaller as the people from the incubator a) already did some screening (only the most viables startups access the incubators) and b) the startup members get advice and mentoring so again, their "chance to survive" increases.

But still:

a) it's not because a startup didn't participate to any incubator that the business idea / team / execution / ... are wrong or worse!

b) there is really not enough incubators to take all viable and probably profitable startups in

If the startup presents a good opportunity and does a minimum of marketing (or some search for investor), it will be found by VC or by an angel. They know how to find and evaluate an opportunity...