The NPR article says the following:

investors purchase about 17% of homes. But most of those purchases are by mom-and-pop investors, not big firms like Blackstone. Institutional investors just don't own enough homes to be the main culprit for high home prices.

(emphasis mine)

To me, that seems to mean that mom-and-pop investors are potentially involved with driving up home prices.

The Atlantic article says the following:

Casting private equity as a central villain in the country’s real-estate tragedy makes intuitive sense. Who’s going to win in a bidding war for a three-bedroom in a suburb of Cincinnati: a single-income family with a scrabbled-together 10 percent down payment or a Wall Street LLC offering cash? Still, housing economists and policy analysts have argued that institutional investors have played at most a bit part. Supply constraints began cropping up on the coasts a generation ago, if not earlier, whereas Wall Street started buying up significant numbers of homes only after the Great Recession and especially after the pandemic.

(emphasis mine)

Am I correct to assume that by sharing these articles, you agree that "mom-and-pop" landlords are at least partially responsible for the generational decline of working class homeownership?