Spurs, can be very helpful with some horses, maybe green but should never be used a lot. Spurs are for advanced riders with a good leg. It can be more useful than a crop.
I’ve only ever used a crop. I don’t think that spurs are nessacary unless jumping over 1m and if you’re a experienced rider! They are NOT AN ESSENTIAL!
Spurs put better equal pressure on the horse where as a crop puts pressure on one side only. Both should only be used under instruction supervision or with a very experienced rider and horse
May I Suggest that you uses them on and off to reinforce your aids. But so you don’t become dependent on them.
As Caoimhe said, if well used they are both helpers, they help to reinforce your aids! There are a lot of spurs to all types of horses and riders! I have different spurs for diferent horses, I use them everyday!
I don't think spurs and crops should be compared. Used properly, spurs should refine the aids, whereas a crop is to reinforce the aids. With proper use of both, I am not against either. However, I do believe they should be removed from people who cannot use them.