There are a lot of things to consider regarding this question.
The first is that it is assumed that Apple no longer makes computers. That is absolutely not true. Apple makes more computers than anyone else even today. The only issue is that the devices are a lot smaller these days in the guise of the Mac Mini, Macbook & MacBook Pro and of course iPad and iPhone which are Apple’s biggest sellers. The reason they are the biggest seller is because Apple’s target market today is the average consumer and not the Mac desktop user of yesteryear since MacBooks, iPad & iPhones make up the bulk (over 80%) of Apple’s profits. The computing user base (for them) has shifted quite a bit from desktops to smartphones since 2007 hence there’s less demand for big systems like Mac Pros these days.
Plus building and designing a system isn’t easy. There’s also some tech supply, staffing and geo-related issues in this equation. The quality of the labour force and engineers is one, and quality of supply and manufacturing is another but so is the cost of having both. Products for Apple are increasingly being made in the Far East in China and now Malaysia due to cost, quality and skill issues, but the tensions highlighted in the recent U.S.-China tech investment tug-of-war will only bring difficulties to both sides. To build good products you need good engineers but without money they all mean nothing. Apple has already shifted Mac Pro manufacturing back to the US today to meet consumer demand but it remains for how long (since it adds thousands to the end user cost of buying the Mac Pro).
As a former Powermac G4, G5 & Mac Pro 2008 owner I too, do sometimes wish they make better machines but unfortunately money talks and from Apple’s viewpoint because Mac Pros make less than what the iPhone & iPad does (less than 25% profit) to them Mac desktop users are considered a minority, hence the reason why we haven’t seen new designs lately for the Mac Pro (excluding the Mac Studio of course, which is a totally new category of desktop system). Hope that answers your question.