2 thoughts on YC, 1 on the company.
ON YC:
YC's model is: place lots of small bets. They have presumably grown considerably in the last 10+ years, and are likely now managing a lot more capital than they were initially, which means they need to place many more tiny bets than they initially were. YC accepts many teams who just apply as a team.
In other words, YC is not really in the business of evaluating ideas; they evaluate founders and give them money depending probably 80% on the founding team and 20% on the idea.
ON THE COMPANY:
On the company/product, calendar-ing is a relatively high leverage problem. Everyone on the (digital) planet uses a calendar every single day. Scheduling stuff is a nightmare. Being on time for stuff is a nightmare. Apple Calendar sucks. Google Calendar sucks. I assume Microsoft Office calendar also sucks. If you solve this problem in a better way to the extent people are willing to pay for it (not to be underestimated, see Superhuman), there is a large direct and indirect market for such software. Now, if you have a successful calendar app, you could do something like calendly, which is already a billion dollar company.
Try to remember, a lot of companies that come out of YC are in MONTH 3 of their lifecycle. The initial footprint can look small, but dig a little deeper and a lot there. Small footprint, big ideas.