You are right most motherboards can be easily fixed. They contain tiny fuses. They look like miniature rectangular brick-like chips They are on the circuit leading to; or, located next; to the failed component; look up chip fuses on search engines to see a picture of them as, they come in many guises. most have a "000" or, F1, F2 etc. designation but, not all do, some , especially HP motherboards have white ones with the designation P10.
A schematic can show you where they are. They are very hard to replace as they are surface mounted but, with some study, and; a hot air smt repair station; you can do your own repairs.
In conclusion: if your motherboard is dead or, especially if only one component: i.e. wireless or, usb socket stops working (not big removable parts like: dvd drives, memory etc.) you may be able to fix it yourself. So, ; Get out the magnifying glass and, start looking for those fuses first!
Hope this helps!