This is simply not true as well. CS majors also can begin serious work with just a BS degree. I have no idea what school(s) the parent topic is refering to but remind me not to recommend people go there...

Four years is a LOT of time to get deep on multiple CS topics not just a broad overview. If you finish 4 years of serious study and don't have deep knowledge of a few things you did college wrong.

College is the only time in your adult life where your only job is to learn. It is incredible that many of us get that opportunity and that some people come out of it with just broad knowledge is disappointing.

In my CS program, senior and most of junior year were almost entirely specialized courses where we had a choice to pick a topic that interests us and deep dive. (AI, graphics, networking, bioinformatics, big data, programming language theory, etc). All the general studies were mostly done by the end of sophomore year.

You could have two identical ME grads go on to specialize in completely different things. One guy might spend his entire career working on hypoid gear sets and another might work exclusively on marine diesel rotating assemblies.

Ditto for EE, CE and so on.