I posted the following in a quotes page a few months back. I don't know how justifiable these were, and these are only questionably pessimism, but there may be some interesting examples in this. In particular, my light knowledge of the subject suggests that there really were extremely compelling reasons to disregard Feynman's formulation of QED for many years after it was first introduced.

It is interesting to note that Bohr was an outspoken critic of Einstein's light quantum (prior to 1924), that he mercilessly denounced Schrodinger's equation, discouraged Dirac's work on the relativist electron theory (telling him, incorrectly, that Klein and Gordon had already succeeded), opposed Pauli's introduction of the neutrino, ridiculed Yukawa's theory of the meson, and disparaged Feynman's approach to quantum electrodynamics.

[Footnote to: "This was a most disturbing result. Niels Bohr (not for the first time) was ready to abandon the law of conservation of energy". The disturbing result refers to the observations of electron energies in beta-decay prior to hypothesizing the existence of neutrinos.]

-David Griffiths, Introduction to Elementary Particles, 2008 page 24