Yes. The reason is lazy people expect to be able to ask five questions in one go and expect one single answer to answer all five of them.
The key is to realize that submitting a query is to ask a question. So how many queries to you think you have to issue if the number of questions you have is five ?
It is technically perfectly possible to "ask five questions at the same time" to any given truly relational DBMS. Said DBMS will give five answers at the same time (and not leave you to guess which answer corresponds to which question). That SQL doesn't do it, does not mean it's impossible.
The key is to realize that submitting a query is to ask a question. So how many queries to you think you have to issue if the number of questions you have is five ?
It is technically perfectly possible to "ask five questions at the same time" to any given truly relational DBMS. Said DBMS will give five answers at the same time (and not leave you to guess which answer corresponds to which question). That SQL doesn't do it, does not mean it's impossible.