So the Officer says to the crowd "Per House Enrolled Act 1186 I am ordering all of you to stand back 21 feet or you will be arrested. I only have one pair of handcuffs and I see there are 15 of you so please consider all of yourselves under arrest and watch peacefully until my backup arrives".
Got to love dumb laws.
1) I always carried 2 pairs of handcuffs on my person and 2 more in the car (spotlight handle), and a hobble and usually leg chains, plus some zip ties, when they became a thing.
2) I most often knew the players, if only by face. Going back for them later works well as a deterrent when they know that's an option. Kind of like Tasers. The threat of being tased actually works better than the actual tasing. Word gets out and the law, if utilized openly a few times, will act as a deterrent.
Another aside: My favorite Taser arrest was when I had a chronic small time crackhead burglar semi-cornered. While he was deciding which way to flee, I advised the suspect that if he failed to comply with my order to get on the ground, I would be forced to utilize my Taser on the posterior portion of his anatomy. While not really verbalizing the command in that manner I was holding my hand behind my back as if grasping a Taser. As he had previously taken a ride he decided to comply and submit to arrest. He expressed his displeasure later when I told him I was glad he submitted as I'd forgot my Taser on my bedroom dresser.
3) Even if you can't find them later there is a positive effect because when they think you're looking for them they go into hiding and cause less trouble, at least for a fair while.
4) If they aren't aware you're keeping an eye out for them it's worth it for the surprise factor. - "What are you arresting me for, I didn't do nothin." - "Well remember last Saturday in front of the club!" Plus there's a good chance they're holding now.
A misdemeanor that must be committed in my presence doesn't have to have been committed just then. It's good if you did some sort of documentation originally. It should be even better now with body cams.
When I first worked as the PD in a little podunk town where I couldn't legally pursue outside my jurisdiction I had a traffic infraction fleeing problem. I solved my traffic fleeing problem when I started arresting the perpetrators a week or two later when they came back thinking they had got clean away. Surprise! (A little Mississippi River town now bypassed by the highway).
As mentioned earlier by Muss, the old Mo "Failure to comply with the reasonable request of a police officer" was well utilized back in the day. And probably no longer valid. The Fl "Resisting officer W/O violence" can also be useful but their vagueness can make prosecution difficult. Adding some measurable clarity to the situations the law addresses could be a good thing while still allowing "citizens" the ability to record, from a distance safe for the officer.
If well written I think the law in question is a great law.
I think I'm done here.