For some functions, such as simple timers, one advantage mechanical might have is that it might be easier or cheaper to obtain repair parts.
A mechanical timer is likely to be a commodity part used by many different manufacturers in a variety of products.
An electronic timer is more likely to be a custom board designed by the manufacturer of the appliance you are trying to repair, possibly designed specifically for that model. There might be only one source for replacements, and they may be restricted to "authorized" service companies.
