Why do companies sometimes not use definite articles to refer to their products?

When I was in Malaysia, if I said “I went to school for my master’s degree…” they would correct my English: “That’s not ‘school’, it’s ‘university’ lah.” To call higher education “school,” I realized, is just an Americanism.

It may be an Malaysianism. After all, there is the London School of Economics, and so on.

It’s the same in India. If I referred to “school” (generically) they understood it to mean primary or secondary education, not higher education.

Sure. That’s a style issue, not one of grammar. Meanwhile, my Associate Press Stylebook and Libel Manual says:

So, nothing wrong with it. Just follow your style guide and be consistent. (There’s no entry for HMS).