Because sometimes I do chores that require me to be outside? And I'm constantly going in and out, carrying things back and forth, moving tools from the shed to the garage, to the kitchen to hang a shelf, and back outside to put them away? When I do yard work I get sweaty and need a drink of water, and don't feel like taking off my shoes or boots just to go inside for 30 seconds and then put them back on to go back out and continue working.
Crocs don't do well in wet sadly.
But it honestly depends on what im doing, if i know I'll be in and out the house a lot taking a single path and cleaning that is just easier.
I'm not sure what the problem is when you work in slippers or crocs. I often am barefoot at home but sometimes when it's cold or when I do something that involves water I put on house slippers. When I go outside of the apartment to get the post, to the basement, to the trash, or the balcony, or the garden, I slip out of them and in another set of slippers that are used solely for "outside". This takes like 2 seconds.
And for the water drink when you do yard work, maybe bring a bottle? Might save you even more time than running back and forth to put water in a glass.
Also, I don't know your life, but I doubt that you hang shelves in your kitchen on a daily basis. But I mean, you do you.
You'd be amazed how much work some people do on a daily basis. Also my backyard is currently a swamp, and slippers would not last me a week of working in my garden, even if it were good weather. But you do you.