Computers can't represent 0.1 (in floating point), yet that hasn't stopped anyone from doing finances on their computer.
I don't think this is big news OR a parlor trick. It's just some obscure thing computers can't do that nobody has noticed for 70 years because nobody needed it.
Of course they can. They just can't do it in binary [EDIT: base 2]. But they can certainly do it in (say) BCD [EDIT: base 10].
Yes, generally, but that is just a social convention. There is nothing stopping you from doing floating point in base 10 rather than base 2, and if you do, 0.1 becomes representable exactly. It's just a quirk that 1/10 happens to be a repeating decimal in base 2. It is in no way a reflection of a limitation on computation.
floating point for financial data may have made sense back when my 386 DX CPU has a FP coprocessor and computation were dog slow.
In this day and age though you'll typically be not just a bit but much better using an abstraction that can represent numbers with decimals precisely, which frees you from a great many rounding error, epsilon computation, error propagation, etc.