That's true, but I think of that as a different phenomenon.
Going to music festivals is sort of like pilgrimage as well. But I definitely count it as vacation. People do classic pilgrimages and call that hiking vacation nowadays. Amateur sports events, especially multi-day stage ones, are totally like pilgrimage. You get together with people with common goal, do shit and hang out. I sure as hell count that as vacation.
You are looking at this from the perspective of an atheist living in 2018 and not a deeply religious medieval peasant.
Even including religious component, I don't really see how it differs much from e.g. pilgrimaging to music festivals. I've done quite a bit of traveling where solo task was to see a specific artist. I do count that as vacation :)
What is your definition of vacation? What specifically stops pilgrimage from being a vacation?
You might be conflating shightseeing and vacation as time-off. On top of that, you might want to look into how pilgrimage or other religious get togethers look like.
It's not like people come and pray and do nothing else. In most cases shopping and getting together with people from afar is involved. People have and always had natural needs like roof for the night and food. And rest during the day. If a bunch of people got together at night having a similar goal, they'll probably have a chat and maybe even party a little. There's a reason why many religious sights were surrounded by shopping and entertainment. Even a long time ago.
For example, the very simple act of sunday church. Back when traveling took time, it was certainly a day trip for rural people. It was pretty much a tiny conference or festival for them. That's why market square a frequently next to churches and markets are held on sunday. People come, shop, have a chat... And go to church while at it. I'm talking not only today, but from historical perspective too.
Talking about vacation only as "diversion", I guess quite a few of my vacations wouldn't count then. If I was going to a music festival, diversion itself wouldn't mean jackshit to me. I went to many festivals where I basically got to the location in cheapest possible way. Stayed on festival grounds and then got home in cheapest possible way. I saw no sights nor diversion itself was the point. But boy if it was vacation :)
Same about amateur racing. I get to the location, I race, get some food, sleep it off and go home. Sometimes terrain/location is part of signing up for the specific race. Sometimes I go there just because it's well organised and my friends are going. More likely than not no sights are seen nor I are about location aside from race track much.
Sometimes vacation is purely to get out of daily routine and jut spend time with myself. Diversion itself ain't the point either.
I don't see how amateur racing and attending a concert can meaningfully be distinguished from diversions.
Sure, a super religious nut might make it one. But usually a closest church would provide a fix for that. Let alone that not all were super deeply religious in medieval ages.
What "objective practical need" do you see in Camino de Santiago? [0] It's more or less a spiritual journey, meditation shall I say? And a significant chunk of modern tourism is based on that too. I could definitely say I had "objective practical need" to go to certain concerts or do certain trips. I find especially the later is great way at maintaining mental health and finding peace with oneself.
There's a good saying by bikers that "all you need to solve a problem is a tank of gas". Does it make motorcycle riding (e.g. motorcycle roadtrip vacation) an "objective practical need"?
Your average medieval peasant was much more afraid of his local nobility than of god. Good part of nobility was much more afraid of mortal repercussions rather than the underworld. And clergy... Let's say today's clergy with their scandals is not that different from medieval times.
Do you think protestantism could have happened if people were so deeply religious both towards god and church? Even though god was much more real to many more people, church (and to extent - pilgrimages and church mythology) was seen as separate from god in many cases. There was plenty of questioning going on throughout history.
This view may or may not be affected by the fact that christianity came to my country only in late medieval ages. And took couple hundred years to be established. With remains of the old worldview still surviving in popular culture. People were more than aware that church teaching is not the single one available.
Of course there are more serious traditions of pilgrimage, but people are people, and for every one with a deep connection to their faith, there are others who will use the excuse of pilgrimage for a break from the routine.