As if the Kage Bushin is needed. But lol at this faction of NBers that never give Tobirama any ground in vs debates. It's always the same people.
Trying to add real life logic to this fictional manga doesn't work. Read the first chapter for god's sake.^^^ making a bunch of shadow clones is useless in battle if you don't have a big enough pool to make it worth while.
Let's say you have 200 units of chakra and your most conservative technique takes 35 units of chakra.
By making 10 clones*, you know have 200/10 = 20 units of chakra across every clone while each person(clone and original) is 1/10 of your overall strength. You can't even use your weakest technique anymore and you're now a bunch of weaklings instead of 1 strong person.
That's why multi shadow clone is only useful for someone like naruto; His chakra pool is so massive that he can still use all his techniques after making thousands of clones. And, that's why no one in the series makes more than 2-3 clones at a time - it would become pointless.
*EDIT: Number should be 9 seeing as you have to also count the original user. i.e 9 clones + 1 = 200/10 = 20