Swarmkeeper
Hero
I agree with you about a living world. (Also, I don't know why some DMs seem to think having chests the PCs can't open, secret doors they can't find, lore and history they don't know, and cool items they can't identify or use, makes for a better game experience. )
However, I do think it is partly a system issue, since (in theory) it doesn't happen in Pathfinder because all* the DCs are written into the rules.
It seems, from looking at 5e conversions of Pathfinder adventures, that you get reasonable results if you take the Pathfinder DC (available for free at Archives of Nethys) and reduce it by 5.
Of course, no system can force the DM to actually use the rules in the first place. (I'm as guilty as anyone of estimating the DCs in Pathfinder rather than taking the time to look them up, but I've been playing the game for a long time so my estimates are usually close enough.)
*obviously not every possible DC, but all the ones that come up with any regularity and you can use them to extrapolate the rest
In defense of 5e, rather than giving us a bunch of DC charts to refer to, they keep it simple by giving guidance on how to set a DC for any particular task:
Difficulty | DC |
---|---|
Very Easy | 5 |
Easy | 10 |
Moderate | 15 |
Hard | 20 |
Very Hard | 25 |
Nearly Impossible | 30 |
They even advise:
If the only DCs you ever use are 10, 15, and 20, your game will run just fine.
Then they had to go ahead and muddy the waters with this language:
If you find yourself thinking, "This task is especially hard," you can use a higher DC, but do so with caution and consider the level of the characters.
The "caution" part is good but the "consider the level of the characters" could be misleading people down the path of DC creep which @ph0rk mentions above.
Also, obligatory mention of: "no one reads the DMG anyway"