This is where labels fuck up when they do not see the benefit of catalog sales and
just market their crap for a quick return. Good records will continue to rake in sales
for decades to come.
Wellllll, yeah. But that's kind of easy to say now, with 35 years of history between now and then. How many marathon-type sellers had there been by the early 70s that they could even see that as a viable option? MAYBE the Velvet Underground? Remember that the very LP format was (I think) less than 20 years old at that point, so there probably hadn't been many examples of initial flops making back their dough over several years.
Ultimately, these people's jobs depend on immediate sellers. You can't go into a performance review and say, I released all these great records, but they won't make back their money for years and years and years because all that really matters is what you've done for the shareholders lately. If a company's not making money they're not making money, you're going to get fired, and the next guy who comes along and gets all the residual sales will take credit for "aggressive catalog management" or some shit.
And yeah, retail sales reports (at least, judging by the publishing industry) are all lies, from every level. Stores to companies, companies to artists.