3 or 4 can very easily accumulate. For example: HTML, CSS as must know, plus some JS/TS (actually that's 2 langs!) for sprinkles of interactivity, backend in any proper backend language. Oh wait, there is a fifth language, SQL, because we need to access the database. Ah and those few shell scripts we need? Someone's gotta write those too. They may not always be full programming languages, but languages they are, and one needs to know them.