They were arguably the first PC manufacturer to take design seriously and while Macs began to become more difficult to repair beginning with the iMac in 1998, there's no questioning that the component choices (from the external to the internal) lent itself to an increasingly sleek design that eventually led Apple to create the best-in-class laptops and desktops.
This push towards sleek design also gave Apple the chops to create the original iPod in the first place...which eventually lead to the revolutionary iPhone...which completely upended the mobile phone industry.
As a PC fan, I love creating and building my own box...carefully selecting my motherboard, case, processor, and memory in the process...and I rest easy knowing I can upgrade my machine over time...
But I wouldn't question the value that highly integrated designs that Apple and others have brought to the table. You can feel the quality in the products they make. There's a lot of careful thought and design. Modularity and repairability are a necessary sacrifice to build products that sleek.
Take a look at the failed Project Ara by Google: https://atap.google.com/ara/. It would have brought modular parts and design to the mobile phone industry. While a great concept, and something that appeals to my custom rig PC roots, it may not actually have been that useful in practice for the vast majority of the general public.