With display:table from CSS 2 you could do the layouts you could do with HTML tables. Flexbox solves a different problem - for example you can't have rows and c

With display:table from CSS 2 you could do the layouts you could do with HTML tables. Flexbox solves a different problem - for example you can't have rows and column in a flex. There is some overlap in functionality, but generally flex is more convenient to use.