They added tons of stuff that made business sense to them. Apparently, matrices as built-in types didn’t. Nowadays, the language is powerful enough to implement them as a library (e.g. https://www.freevbcode.com/ShowCode.asp?ID=3682. Operator overloading became possible at some time, too. https://docs.microsoft.com/en-us/dotnet/visual-basic/program...)

It’s not as if they don’t know matrices exist. Excel has matrix operations (https://support.microsoft.com/en-us/office/mmult-function-40...)