Phase 1's are really not that hard to get, and the process is not nearly as stifling as you are alluding too. Most people without prior funding or reputation don't just get instant money from VCs. Convincing them to give you money can take a decent amount of time too. Especially if you are trying to do something actually out of the box not just something like "Its like UBER but for ..." Just speculating, but I would bet if you are a just starting out and are not well connected getting a phase 1 would be easier than getting VC funding.
Another major plus is that SBIR's don't have to be the next google. You can get funded for a product with fairly mild potential. VCs only seem to care about the 100x investment.
I can only speak from my experience, which is watching a good friend go through the process. It's been very lengthy for them.
You're right that it takes time in many or most cases to get funding from a VC - but they can write a check the same day - that was my point. And there are a lot of them to go pitch your idea to as well.
Another major plus is that SBIR's don't have to be the next google. You can get funded for a product with fairly mild potential. VCs only seem to care about the 100x investment.