HN has had an anti=Yahoo bias for a long time; the reasoning behind the bias keep changing ("layoffs", "delicious", "WFH", etc.), but it always seems to be there.
Your comment doesn't make it clear if you realize just how much bigger Google is than Yahoo. Google is worth $300B, Yahoo around $30B.
The reasoning doesn't change, just the examples.
See Also: snide comments about Microsoft.
Generalisations are dangerous, but I think the people on HN generally aren't Yahoo fans because traditionally they don't appear to value good engineering.
PG summarised it quite well:
But Yahoo also had another problem that made it hard to change directions. They'd been thrown off balance from the start by their ambivalence about being a technology company....The worst consequence of trying to be a media company was that they didn't take programming seriously enough....Yahoo treated programming as a commodity....One obvious result of this practice was that when Yahoo built things, they often weren't very good. But that wasn't the worst problem. The worst problem was that they hired bad programmers.