From 1988 to 1990, I think, there was a three-year freeze on the regulations for the sake of consistency.
McLaren dominated all three years and the rest of the field were barely any closer to them at the end of the last season than at the beginning of the first. So the evidence suggests that a regulation freeze would not allow smaller teams to catch up, it would just retain the status quo.
Conversely, the regulation shake-ups (e.g. 1998, 2005, 2009) have allowed different teams to move to the front, by testing who can make the best interpretation of the new rules.