Well, you could walk it all, and some do. Some people even count their daily steps and log those. The point is that it's not a race, or a competition – it's a personal challenge. And if 'pootling' 874 miles is not a challenge for you, then don't sign up. Most people are fitting it in around other constraints or demands on their time: jobs, studies, children, illness, disability, isolation, etc. I took 4 months off over the summer to focus on other activities and ended up with 350 miles to run in 2 months, which was a challenge for me, and I'm proud of the way I managed my time and achieved my goal. If I'd counted my dog walks and all the other walking I do every day I could have done the distance in a couple of months at the beginning of the year, but I chose to do it in a way that pushed me out of my comfort zone; I wouldn't dream of dismissing anyone else's parameters for their own personal challenge.
It's like parkrun – I have as much respect for the people who show up week after week and do it for their own reasons and in their own time, however long it takes them, as I do for those who set course records. No one needs to compare themselves to anyone else.
And you don't have to take a full year to do it anyway. The first finisher on LEJOG9 did it within a month, which is the equivalent of more than a marathon every single day.
Anyway, Happy New Year to all, and good luck to anyone setting themselves individual challenges for 2022 
PS @Alargeoneplease several cocktails down, already signed up for the WCP! 