Maybe a better way to put it is how people fitness train. Some run a couple miles a couple of times a week. Others crosstrain, often doing over 100 miles a week between running and biking.
There are certainly ornamental titles in IPO, usually obtained by someone who wants to be able to breed their dog. There are also people who are very serious about IPO, and bring more pressure on the dog to invoke a more serious response. Not all IPO dogs can handle this. When done correctly, an IPO dog will be balanced and confident, and more than able to protect you should the occasion arise.
If there is no measure of success, no benchmark (titles and scores) in IPO, how are you able to measure your success relative to others?
I have not done formal protection training but I think the scope of the training is much narrower than advanced IPO training.