the fact remains that 90% of the time you are given that phrase its for 'separation assurance', and the other 10% of the time it's for separation, period.
I call BS. Not down here in Mexico. We can put in a plan to transit and frequently be denied for a host of reasons, usually because they are "too busy." Assumptions made about the weather by ATC are also a common reason for being denied. Just because everyone is IFR into Tulla quite obviously means that everwhere else must clagged in too
