Each to their own with all things fishing.
Don't take offence but I am aware of the fact that swivels don't run very good through runners so if needed I would use a different setup to allow for a longer leader. I just use a swivel as thats what suits me most of the time.
I am in no way saying using a swivel is the best or the only way to join mono it is only another idea. I think everyone who has commented here has suggested something different which is great as it gives lots of choices.
Ronnie