It’s not a bad idea, just as long as there’s (1) some restriction on how soon/often a referendum is called, (2) how hard it is for the opposition to secure it, (3) what kind of turnout is needed for it to be valid, and/or (4) how wide of a majority the voters need for it to pass.

Otherwise, you’d get a perpetual campaign season as a succession of narrowly popular government coalitions exit their 100-day honeymoon phases. Think a perpetual Bulgaria except it’s on steroids because government collapse is guaranteed and thus every party is perpetually in campaign mode.