Even when MySQL development velocity was more rapid, they maintained binary table format compatibility across major version upgrades the vast majority of the time. Literally the only exception I can think of, which necessitated a table rebuild, was the fractional timestamp storage change when going from MySQL 5.5 (2010) to 5.6 (2013).
Mostly because MySQL development is slower.
Even when MySQL development velocity was more rapid, they maintained binary table format compatibility across major version upgrades the vast majority of the time. Literally the only exception I can think of, which necessitated a table rebuild, was the fractional timestamp storage change when going from MySQL 5.5 (2010) to 5.6 (2013).