This is actually a pretty rampant and under-discussed problem in SV. Exaggerated metrics in investor pitches are so commonplace that NOT exaggerating your metrics actually puts your company at a real disadvantage (because investors assume you're worse than you portray).
The first root cause is that a lot of this lying goes unpunished because investors are afraid to ruin their reputations (founders won't want to work with investors who sue the companies they invest in).
The second root cause is that investors on-average still make a lot of money, so they see this behavior as a cost of doing business.
I'm not sure what the solution is, but the fine line between positive framing and intentionally misleading investors is crossed way too much, and in the long run, it hurts both the founder and investor community.