JacktheRabbit
Explorer
Magic items are intended to be rare and iconic in 5E, not something we assume everyone has. Sit down with the DMG, go through the recommendations on treasure and then randomly generate appropriate treasure for a 5 PC party over all 20 levels. You'll end up with an average that approaches what you see in XGtE.
Whether PCs can find a market to use money to buy items is up to the DM, but it is not necessary.
So - yeah - one rare magic item for a party at 10th level does seem ok.
And in 6E they may be candy again.
Who cares. Do what you want and enjoy the game. It only really matters if you mix Wizards printed material and homebrew material as the former is balanced around the rather meager amount of magic given and can quickly become too easy if during your between module sessions the party gains too much gear.
Oh and by the way "MOST" players like cookies. Magic items are fun cookies, far too many DMs commenting here seem to only consider what they want. I do not see many people commenting about balancing loot around what they players enjoy.