NYPD Blue was the same way, especially for the wave of actors on HBO shows later in the 1990s and 2000s.
Whereas Blue Bloods appears to be a retirement home for Sopranos characters. Just off the top of my head - Gene Pontecorvo, Artie, Patsy Parisi, Agent Harris to name a few.
The bigger the show, the more exposure future stars tend to receive. Look at Cheers. Harry Anderson and Fred Dryer were regulars who later appeared on their own successful shows.
Then of course, there was Seinfeld. It launched Courtney Cox, Teri Hatcher, Bryan Cranston, the woman from Law & Order SVU, Debra Messing, and Megan Mullally to name a few.
