Of course it’s better than not having the write-off. But it’s not like it’s free.
Business expenses aren’t profit so they aren’t taxed because it’s money you didn’t actually make.
Since most businesses operate on a small margin, removing tax deductions would make tax burdens higher than profits.
And it’s not like that camera lens isn’t being taxed. I’m buying it from a company that pays taxes on its profits and payroll and whose employees pay taxes, and on top of that I’m paying sales tax (to a different entity of course).