While I like what she did on the truck, you've got to remember that it is a YouTube channel. She makes her money off producing content. Doing an ECU swap to MEgasquirt is going to produce more content and garner more views than repairing/replacing a few capacitors on the factory ECU.
Honestly I can't blame her for doing the swap even if fixing the factory ecu was feasible. Given advancements in EFI technology the megasquirt is a lot more capable unit than factory. Megasquirt on it's own isn;t that expensive to get into, atleast not the older DIY kind. The unit she installed is made by a third party, stinger performance engineering, and modified to plug iun place of the early ford ECUs. To buy a new one now is around $900, but the one she installed looked to be a used older version to me, and they are much more affordable like that.
Add to this the fact that most people who would put that much effort into a vehicle that age are also interested in possibly tuning the engine. That makes Megasquirt based solution even more enticing. One of the biggest names in tuning those older Fords is Moates, they have pretty much been the go to for tuning hardware for them for quite a while since most others have moved onto newer platforms and left these old work horses behind. Well Moates closed their doors this month, apparently they haven't been able to sell much for a while due to supply chain issues (the whole chip shortage thing). Rather than creating an inferior product they decided that they had done enough and it was time to go out on a high note.
Given the cost of getting a ECU replaced or repaired for those that can't do it themselves ($$$) and the cost of a tuning solution ($$$), spending a little more on a used PnP MS unit makes sense. That said, if you're going to build a DIY MS (if they are even still available somewhere) you've got the skills to repair your ECU for a lot less.