Welcome to the forums Blackshield.
Back in the early nineties a one second grab rule was introduced in the some tournaments. This suited us very well as we had a nasty habit of grabbing anyway and were always getting warned for it. Turned out people who were good at the grabbing could really use it to their advantage over those that werent and there were KOs a plenty.
As a result of this the rule weas rescinded and no grabbing allowed. Now everyone who had learnt it had to unlearn it and over time they did. So that should answer the a) part of your question I hope.
The answer to b) is simply this - any rule set is limiting (unless the rule is there are no rules

). I have sparred with TKD people and not being able to kick a low kick, which is bread and butter for Kyokushin people, was really hard.
I hope this helps.