Question

If in a Galvanic cell ,say Daniell cell an inert platinum is used instead of a salt bridge why won't the cell still produce a potential

Answer 1

The platinum bridge conducts electrons only, and yes, there would have to be two new redox reactions at the Pt-electrolyte interface, which can contaminate one or both solutions.

A salt bridge conducts ions, so no redox reaction is possible unless the ions flowing in opposite directions can react with one another. But you get to choose the salt in the bridge so that can't happen.