That is incorrect. There was never a reason to ban an aid that allows a vehicle to go faster, it is racing after all
Nope. A lot of it is to slow the cars down because they were dangerously fast.
(Especially in Rally driving where whole groups of cars were eliminated in the 1990s purely for safety reasons).
In Formula 1 there's been a lot of recent changes to reduce the cost of competing, otherwise the team with the most money would always win. eg. Rich teams used to use up an engine in three laps of qualifying just to try and get pole position. Now they're limited to a few engines per season.