Both yes & no...
Stars absolutley matter, but they don't exclusively matter...
There are high rated 4/5-star kids that will bust & there are low rated 3-star kids who will excel greatly & become big time players.
There's dozens of other variables that factor in how kids develop and how well they'll play within a system, their star rating doesn't determine how they'll grow into their full maximum potentiality.
Star ratings are simply a measuring stick of potential talent & ability, it's not the final defining meter of how good a player is or isn't...
There's things that Websites don't know about players, like their background, home life & family circumstances they come from, or how hungry they are to be something.
The
#1 rusher in the Nation was not a 5-star RB, a lot of that has to do with system/Offense he plays in, but based on star ratings coming out of high school, no one would assume he would end up being a 2,000yd rusher.
A player like Ray Lewis who was extremely productive in High School both in Football & Wrestling probably would be a 4/5-star LB/ATH coming out of school today, but that would be based on how great a player he was & phenomenal athletic ability...
What couldn't be measured was what drove him to be such a great player on the field, which was his crazy home life with his Mom & being dirt poor, these recruiting sites don't know anything about that (not that they should), but heart, drive, & determination are things that simply cannot be predicted by anyone.
A lot of high rated kids grew up pampered, entitled & never amount to ****... Rivals, Scout or ESPN can't tell you that in their rankings.
There's a lot of 3-star kids who have a big chip on their shoulder & are going to outwork a 5-star kid all **** day...
Ultimately, "Stars do matter", but its not the ONLY thing that matters when evaluating a player.