Do we need a new necessity added to PACE 'to prevent further offences'?

The recent thread around S35 dispersals got me thinking. If you had a person who was insistent on coming back into the dispersal zone (and did so), but otherwise was fully cooperative, how would you deal? If you were to arrest what necessity is there? They'll give you their name and address, noone is at risk of harm, happy to come in for a caution plus 3.

Same for low level public order, D&D etc..

Do you think a new arrest necessity is required, is there something I'm missing this achieves the same thing or am I simply over clthinking it!