Mykhailo Hrushevsky presented the classic Ukrainian argument against this (which I am not necessarily endorsing here) in
http://likbez.org.ua/en/hrushevsky_east_slavs.html
"...In the first place, it is most irrational to link the old history of the Southern tribes, of the Kievan State and their socio-political organization, laws and culture with the Volodimir-Moscow Principality of the 13th and 14th centuries, as though the latter were the continuation of the first. This may have been permissible insofar as the Moscow scribes were concerned. The genealogical approach may have satisfied them.
Modern science, however, looks for genetic connections and thus has no right to unite the ‘Kievan Period’ with the ‘Volodimir Period’ (as they are inappropriately called), as phases of the same political and cultural process.
"We know that the Kievan State, its laws and culture, were the creation of one nationality, the Ukrainian-Ruś, while the Volodimir-Moscow State was the creation of another nationality, the Great Russian
[3]. The Pogodin theory aimed to eliminate this difference by suggesting that the Dnieper regions of the 10th-12th centuries were colonized by Great Russians who emigrated from there in the 13th-14th centuries, but I doubt whether anybody today will defend the old historical scheme on the basis of this risky and almost neglected theory. The Kievan Period did not pass into the Voiodimir-Moscow Period, but into the Galician-Volhynian Period of the 13th century and later into the Lithuanian-Polish of the 14th-16th centuries.
"The Volodimir-Moscow State was neither the successor nor the inheritor of the Kievan State. It grew out of its own roots and the relations of the Kievan State toward it may more accurately be compared to the relations that existed between Rome and the Gaul provinces than described as two successive periods in the political and cultural life of France. The Kievan government transplanted onto Great Russian soil the forms of a socio-political system, its laws and culture – all nurtured in the course of its own historical process; but this does not mean that the Kievan State should be included in the history of the Great Russian nationality. The ethnographic and historical proximity of the two nationalities, the Ukrainian and the Great Russian, should not give cause for confusing the two. Each lived its own life above and beyond their historical contacts and encounters..."