The assumption that markets are mostly competitive is deeply flawed. Markets are controlled, managed and monopolized more often than not, via strategies like control of chokepoints (computer chip production is a case example), interlocking boards of directors of major corporations, government subsidies for specific industries (and import tariffs as well), etc.
Case example: acceptable cell phones could be produced today that would last for 20 years using the same internal structure, with decent audio/video capabilities and memory storage, if they were designed to be easily repairable, i.e. if the components that are likely to wear out could be easily replaced (battery, touchscreen, etc.). The operating systems could be locked-in to a standard format, or OS upgrades could be made backwards-compatible.
Major phone manufacturers really are not interested in making such devices, because new sales would fall:
https://www.vice.com/en/article/zmd9a5/tim-cook-to-investors...
Where is the competitive market providing the long-lived alternatives?