>>724087010
Grindy? Yes. Idle? If you want to.
No one is stopping you from powermining iron but you lose smithing xp or possible money. Or tick mine granite if you are insane. Most likely you'll hang out in Morherload Mine or Blast Mine, maybe Amethysts to afk more.

OSRS is balance of
>Time(aka xp/hour)
>Attention(apm)
>Resources(either gaining or losing while getting xp)
>Requirements(Quests, item upgrades, achievement diaries, etc.)
for xp rates. Some stuff is more or less "obsolete" but even they have usually collection log unlocks if nothing else, or better xp rates requires quests or such.
For example everyone's favorite skill: Runecraft.
You can mine your essence yourself and craft highest runes. But essence mining is slow. Well you can also buy them but that costs money(not that much tho). Or do bossing for possible drops but that requires combat things. You can also do something like easy Temple Trek, but that needs few quests done.
And fastest xp for is to make lava runes, but that needs lunar spell book and binding necklaces for best xp rates.
However many does Guardians of the Rift, as it has unlocks and costs no resources, plus you get different runes. It is technically the best one for xp/resource balance but you cannot choose that well what runes to make. You can also do slower xp rates but make money with it.
Smithing has turning gold ore in gold bars at blast furnace but you lose money on both paying for it and gold bars having no value. It's also very active.
Or you can do Giant's Foundry for for good xp but it's resource intensive and needs some attention, though you also get gold and unlocks.
Or you can just afk smelt cannonballs for profit(preferably bit faster cannonballs with Giant's Foundry double ammo mould).

It's that kind of fun balance that makes you interact with quests and stuff. On other MMOs you rush to newest raids for best unlocks and that's it. All earlier content is obsolete and low levels are considered worst times in other MMOs