"Now grab a 3ft section of copper tubing, cut it to length with your pipe cutter, bend it with your copper bending tool, and flare it with your flare clamp... what, you don't have any of those? Wellll.."
Source: had to retile a bit of a floor, too small to interest a real tiler. Guess how it looks now?
That part of the business model worked well for Home Depot.
Also, most light everyday home maintenance work like laying tile, building a fence, framing a wall, installing plumbing, etc. is not rocket science. You don't have to be Bob Vila or go to trade school for years to learn how to do it.
I always tell people wanting to do a job themselves that the first time your costs are the same as hiring a pro, but the second time you own the tools and it is just time.