That is a total BS statement.
I do most of the plumbing myself and it only requires me one trip most of the time. Unless the store does not have the part I need. Household plumbing is extremely simple comparing to software development. It usually takes me longer than it would take a plumber to do similar job. I usually do it better and don't have to come back to fix things as it happens with plumbers. That is because I care and want to do things right.
The only time I would hire a plumber is where I tried it myself and I can't undo the fitting. If the job needs heat or pipe soldering in tight spaces. Any time two fittings come apart I can do the job myself. Replacing toilets, valves, faucets, etc., I can do myself. Highly recommend learning this skill, saves a lot of money and you get satisfaction of doing something yourself.
I replaced washing machine just a few weeks ago and it took me one trip to the store to get the new hoses because I did not want to use cheap hoses that come included with the new machine.