Before it burned, Charlie Springer’s house contained 18,000 vinyl LPs, 12,000 CDs, 10,000 45s, 4,000 cassettes, 600 78s, 150 8-tracks, hundreds of signed musical posters, and about 100 gold records.

If it felt like “Saturday Night Live” took to the airwaves in 1975 with a renegade spirit, 50 years later it’s become not only a late-night tradition, but traditional. Hitting the half-century mark is ...