I AM against unlimited substitutions in regular season and state cup matches. For tournaments and showcases I am for unlimited substitution.
If you have 11, good, well-conditoned players you should be able to succeed and you should be rewarded with a good result. If you are playing against a team of 18 who shuffles them in and out, in an effort to get a result through high-pressure, it messes up the beauty and flow of the game (with all the stoppages for subs).
Now, if that team is fit, and can be successful playing high-pressure with 11 starters and three to five (pick a number) subs, with no re-entry, I tip my hat to them.