So, the milb career of the HS player Shoveit posted is very informative and also typical of the path of the overwhelming number of HS signees.
For families even considering signing from HS, the seeming advantage of an early pro start is basically a mirage - especially compared to what a HS signeee gives up.
Four years in and the HS player made high A; note that the biggest jump is to AA and his stats dont get him there (yet). Four years in, the college (4 yr) player has whatever 3 college years brought in course credits (typically 2.5 - 3 yrs worth), and one season in milb (most likely SS). Both report this spring; the HS player is ticketed to high A; the college player has a legit shot at high A, but most likely will be assigned to low A full season. So, passing on college was worth - most likely - one season advantage. AND the HS player has been forced to mature in milb; the CP matured in the half-way house known as college.
(Pitchers may even essentially lose that first draft season (whether HS or college) due to limits on innings.)
While one size doesn't necessarily fit all, fewer options are burned by going to college and there are few real advantages for passing on college ball.
Imo.