From 2019 to 2022 I helped out a friend with a computer shop (viral issues with staff) by fixing PCs and laptops. I had a power supply tester and a handful of universal laptop power supplies but that was it. No DMM, no soldering iron, no scope. The only other tools were hand tools. I fixed on average 2 PCs and 3 laptops a day for nearly 3 years. Never once did I require a DMM or any other instrument. In general, component level repair is not practical. Most people will not spend the money to pay the labor + parts to diagnose and repair a MB or a peripheral controller in this commodity driven business and you'll need a whole lot more than a DMM to do that kind of work. Scopes, logic analyzers, lab grade power supplies, at least 2 DMMs, SMD re-work station, temperature controlled soldering iron, a supply of solders, solder pastes, fluxes, etc., etc... and time the customer will need to pay for.
That said, a $25 DMM will last about a week in the hands of a road tech.