Things I never track unless expected to and never ask players to track:
-Gold for mundane purchases
-Encumberance unless they are trying to transport something really big
-Food/water unless they are in a dire environment or situation
One of our other players LIKES to track the above, but they generally like simulations with intricate micromanagement.
Tracking stuff like that varies between groups and games. Heck, how much I track varies depending on the theme of the campaign.
When my group was big damn heroes I never bothered with food or upkeep, especially since the party was very much vagabonds. And in my more Everyman Ravenloft campaign, I concerned the players with ammunition, rent, and spell components but not food, since they were seldom away from civilization for more than a day. My current campaign is pirates, so that stuff all falls to the wayside because boat.
But I've also played in a heavy sim game where tracking food and encuberance was a big part of the game, and spending a week in a dungeon was a huge chore since everyone had to carry tonnes of lantern oil and packs of food, and large amounts of the player's wealth was spent on food, replacing damaged clothing and gear, and the like.
And my next campaign will have a lot more tracking: the world is a homebrew that adds a dash of post-apocalypse to D&D and resources are not readily available in all regions. Tracking more minutiae emphasises the tone of the campaign, and the players have to actually plan ahead and consider their travel time.
Lord of the Rings provides an excellent example of both styles of game. Food is seldom mentioned early on, even when the party is travelling through Moria for days or on the road for weeks. Because there are regular stops in town. And when Aragorn, Gimli, and Legolas are dashing across Rohan and Gondor they never concern themselves with that stuff. Or even looting gold, really. In contrast, when Sam and Frodo enter Mordor food is a regular concern and rationing supplies is important. Because stopping for supplies isn't an option.
I can understand *some* games not tracking it. But if every game does away upkeep and downtime, that just feels a little samey. I've done the "brave uber-heroes save the world" campaign a couple times already, why play it again? The game where the players are awarded with a keep that they have to repair, then have to defending the surrounding farms, and defeat local menaces could be interesting. As could the game where the player characters are business owners and working on expanding their supply chains. Having the innkeeper be a retired adventurer is a common trope, but why end the game there? The innkeeper might just leave the tavern in the hands of a manager and head into labyrinthine depths in search of fortune and glory.
One of the major literary types of conflict is Man Versus Nature. This is is very much struggling against the environment, worrying about food and exposure and the like. In D&D this is a big part of the exploration pillar, arguably a third of the game. Heck, the entire world of Dark Sun uses this as a major theme. It's exploratory combat, and potentially eats into spells and resources. Not tracking limited resources makes the game much easier. It makes hostile environments (dungeon, deserts, the underdark) less inhospitable. It's basically playing D&D on easy mode.
Why is tracking resources in Man Versus Man conflict (i.e. combat and. fighting monsters) acceptable but other forms of tracking a hassle?
Having to balance the food you need for a journey versus the weight you can carry is a form of tension in the game. Having to worry about also finding enough treasure to buy new arrows and food, and planning your journey to hit major towns changes how the story unfolds. Does the party risk travel over the swamp or desert where food will be hard to acquire or take the longer route along the roads where they can stop at every town?
Limited supplies also gives the party a reason to return to town and adds some verisimilitude to the game. I'm sure everyone's had the surprise dungeon adventure where the party accidentally ends up in a dungeon for far longer than expected. Which is fine so long as no one asks "Hey, what have we been eating the last three days?"
And returning to town provides a break in the tone of the game, allowing the players to engage in some roleplaying and not just spend twenty levels away from civilization and living as murder hobos. Some downtime also delays the speed of the campaign. If the PCs rapidly go from dungeon to dungeon or encounter to encounter the entire level 1-20 campaign could occur over as little as 50 days. I ran Rise of the Runelords a while back and that had all the downtime crafting Pathfinder had to offer and lengthy overland travel from one side of the nation to the other and the entire thing still only took five or so months.
Not tracking gold for mundane purchases made sense in 3e and 4e where players get an OMFGWTF amount of gold early on. Tracking food and supplies became unnecessary when the change from the purchase of your +2 magic weapon was enough to buy food for a year.
But it's certainly much more interesting in 5e where mundane purchases can take away a meaningful amount of your wealth.
