Full Idea
Some chemists even suggested that the periodic table would have to be abandoned in favor of a classification system that included a separate place for every single isotope.
Gist of Idea
Some suggested basing the new periodic table on isotopes, not elements
Source
Eric R. Scerri (The Periodic Table [2007], 06 'Intro')
Book Reference
Scerri,Eric R.: 'The Periodic Table' [OUP 2007], p.160
A Reaction
The extreme case is tin, which has 21 isotopes, so is tin a fundamental, or is each of the isotopes a fundamental? Does there have to be a right answer to that? All tin isotopes basically react in the same way, so we stick with the elements table.