They were. E.g. see here for a major, good paper announcing a novel class of superconductors:
https://sci-hub.ru/https://link.springer.com/article/10.1007...
The difference now is that we're seeing a premature preprint being replicated in real time.
Even in that paper, the authors note: "The way the samples have been prepared seems
to be of crucial importance: Michel et al. [21] obtained a single-phase perovskite by mixing the oxides
of La and Cu and BaCOa in an appropriate ratio
and subsequent annealing at 1,000 ~ in air. We also
applied this annealing condition to one of our samples, obtained by the decomposition of the corresponding oxalates, and found no superconductivity." And you can see that in their resistivity/temperature graph of samples prepared using different protocols.
