As I see it, the pointlessness of gold in 5E is just a symptom of a, in my eyes, much bigger problem.
It highlights the incredibly narrow focus on combat 5E has.
Wealth was important in all cultures during most, if not all of written history. It was the driving force for many people and shaped the world as it is now, yet 5E can't find a use for it.
That doesn't only mean spending money to get numerically better but all aspects where wealth would be an asset like in social or economical or even just day to day living are not represented in 5E. It is all about killing things in dungeons and thats it.
And it is not just the absence of any rule or guideline about using wealth, even when you invent some for your campaign when you give the players as much gold as they are supposedly to have anything you could come up with would be trivial as the PCs would be filthy rich and you would need to comically overcharge them for gold to be actually an issue.
Just look at other RPGs like Traveller, Shadowrun or Warhammer. Gold is important as it buys upgrades and all of those settings detail enough things besides combat that there are many uses for gold apart from it.
personally i have not found 5e or any edition of D&D to be all about combat or even killing monsters in dungeons (though of course some of that plays a major role in many if not most campaigns.) I have also only rarely seen a campaign in those editions where gold was not valued and useful within the campaign - often for those very status, wealth gains, acquisitions etc.
generally, gold (whether coins or art of jewelry per the DMG) after the early stages (once the campaign moves more into the heroic levels and up) tends to be the more interaction with setting and influence with setting reward - just as advancing character level and (sometimes) magic items are the more combat focused ones.
I think if one comes to D&D with the idea that It is all about killing things in dungeons and thats it. then its a self-fulfilling prophesy kind of thing. If thats what you expect and what you focus on, thats likely all you will find if you select players and GMs who wear similar blinders.