It was simply unclear whether cloth masks or the simple medical masks would help significantly if the population would wear them. The data about SARS-CoV2 specifically was sparse, and there also wasn't as much about mask effectiveness studied as one might have expected.
And at the same time there was a concern about shortages of PPE like N95/FFP2/KN95 masks. But those were used in a professional setting, with people that are taught how to use them, in direct contact with potentially infectious people and with other measures in place. That is a very different scenario than just giving everyone masks.
Both can be true, that we have good evidence that N95 masks work for professionals in direct contact with patients and in combination with other safety procedures and that we didn't have good evidence that masks (whether N95 or other) would help for regular people.
I think you could have made the justified assumption that masks would very likely help enough to be worth it back then, and some people certainly did that. But the degree to which it would help wasn't certain, and I think the concerns about shifting the supply to places where it was less useful was very real.
The communication about this was messed up in several places, but I think in part because it's two separate issues that seem a bit contradictory at first glance. It's quite hard to communicate that well.