They aren’t inserting junk, they just don’t do anything to rank quality results above the junk anymore. The junk was always there, on page 2 and beyond, and who would ever need to hit those pages. Nowadays I’ll be 15 pages deep and so far off base of the search term that I could write a better index with curl and regex.
The issue isn’t that they are watering down the cream in the milk, it’s that the cream isn’t part of the milk at all now.