> is this really a problem that I'm going to come across in the real-world when 90% of our time is spent ingesting a poorly-formatted csv, doing some quick plots and perhaps building a model to test something out
Yes, multiple dispatch is not some highfalutin ivory tower concept that only comes up in specialized code. For example, the model in question could define custom plotting recipes[1] so that you can just call plot() and have it produce something useful.
Also, why shouldn't dplyr perform comparably against data.table? Seems like there would be no need for a fragmented library ecosystem here if the abstractions the tidyverse is built upon were lower-cost. Moreover, what if my data isn't CSV or in a table-like shape at all? "real world" does not mean the same thing across different domains.