Count checked checkboxes within a query without ARRAYFORMULA

Yesterday I learned what here what to write into cell C1 to get the little table seen in the added screenshot to get the table C1:D4. It's

=ARRAYFORMULA(QUERY({A:A\ B:B*1};"select Col1,sum(Col2) where Col1 is not null group by Col1"))

Can you explain why you need the ARRAYFORMULA function there? Is there a way to simply manipulate my query in C6

=query(A:B;"select A,count(B) where A is not null group by A")

to get the same result? So I only want to manipulate the query string "select A,count(B) where A is not null group by A". I don't want to add an additional ARRAYFORMULA.