Primary among those considerations was that the dendrochronology record is of pretty limited timeframes -- we have very few samples going back more than a couple of hundred years.
And the study of carbon-14/12 ratios in dendrochronology led to deeper questions: there appears to be a significant geographic variation; the change in c14/12 ratio is non-monotonic (i.e. there are times of sufficiently increased historical C14 that samples from that era are indistinguishable from samples in a later era).
This has led to a ton of research into calibration methodologies, leaving many questions that are still open today.