To your question, absolutely there are many bottlenecks and limitations. If you are married and have kids then intensify these 2 factors by a magnitude of 10 maybe, at least in my case, especially if you have a day job that consumes most of your time. Also, you might get stuck some simple stuff that would drain your energy and offset the timelines. Some of the mundane tasks would make you go crazy (imagine coming up with 26 different email templates for the emails that go out...that's mundane). A few ideas where I wasn't 100% sure and felt a cofounder would be someone who would have came in handy on those instances.
On top of all these hurdles, after you launch, you have to do product support along with marketing and getting the word out about your product. Mailchimp campaigns, analyzing Analytic points, testing to make sure things are not broken and a whole lot would keep you on your toes. I feel I can only for that far along but I'm determined to make it to the pole.
I believe the reward is after we sort through all of these hurdles...I can proudly say that "this is me, this is what I've built, all by myself" (Seth Godin's quote except the "all by myself" part).