The advent of SMD components has sadly for many products brought them to a point where on board service is not deemed practicable and thus board replacement is the only service option - a lot of techs won’t do component level service as many LSI’s are too difficult to solder and/or they don’t want to tackle removal and replacement of the smaller IC’s anyway.
Some pro gear suppliers in this country have single city repair centres where the gear has to be returned to that city for warranty repairs, they don’t have repair centres in each state capital - makes it difficult for studios and gigging musicians who don’t have the luxury of a backup $5000 synthesizer or piece of rack gear - unfortunately the time people find this out is when the gear breaks down. The cost to ship a 20Kg keyboard from Sydney to Melbourne is pretty high - don’t throw out the box as it will cost you almost double to ship it in a reinforced flight case.
I do a lot of warranty work for some importers who supply multiple brands to retailers from a single-city distribution centre, as they have come to realise that without proper representation country-wide they are losing repeat customers and recommendation sales or retail outlets won’t sell the product and need to have service agents in other cities. These companies are good with schematics but there are NDA’s that are in place for the service documentation for many brands, so the schematics are likely never to see the light of day on the open net. A lot of gear has the service docs with test point checks to determine fault status and which board needs to be replaced - some list likely component failures with a cross check table.
Some will not release any documentation and rely on board replacement only service - the replaced boards becoming landfill.
In many cases the cost to do on-board repair in labour exceeds the cost of a replacement board and is not supported by warranty.