In some modern field theory texts such as Siegel's Fields it is claimed that canonical quantisation of fields is obsolete as it is not used it modern research papers. Thus, it should be removed from curricula and replaced with more modern methods.
Siegel says that the path integral should be the primary technique taught. However, canonical quantization makes it obvious that the quanta of the fields are particles. I have never seen this done using path integrals. Indeed I have only seen path integrals used for calculating things such as S-matrix elements, which it is certainly much more efficient at.
Essentially my question boils down to this; Can one show the particle content of fields using the path integral? If not, can canonical quantization really be considered obselete when first learning field theory?