I was less so speaking on website metrics and more so on business metrics. Maybe there's more to Mixpanel that I'm not aware of but does it go beyond funnels, website conversions, a/b testing, etc.?
I realize saying "metrics" is a bit broad but I imagine early stage startups track some of these like user-growth, revenue growth, subscription growth to get an idea of how their startup is performing or to help goal-set. Or is this an area where most hack together a spreadsheet that unifies data from external data sources?