Is English your first language???
Pulling up the Druid proficiency list:
Proficiencies
Armor: Light armor, medium armor, shields (druids will not wear armor or use shields made of metal)
Weapons: Clubs, daggers, darts, javelins, maces, quarterstaffs, scimitars, sickles, slings, spears
Tools: Herbalism kit
Saving Throws: Intelligence, Wisdom
Skills: Choose two from
Arcana,
Animal Handling,
Insight,
Medicine,
Nature,
Perception,
Religion, and
Survival
I do not see how you are reading "will not" as indicating a lack of ability or skill as opposed to a personal choice. "Will/will not" implies, to me at least, that somebody is perfectly capable of doing something but chooses not to. The statement "I will not drive a pickup truck" means that I refuse to drive pickup trucks, but it doesn't say anything about my capability to drive them. See what I'm getting at?
Besides, Crawford has come out and said that the metal armour restriction is flavour and doesn't impact the crunch of the Druid's proficiencies in the Sage Advice Compendium, so don't go arguing that "the designers didn't want to give Druids metal armour proficiency", because the lead designer has openly contradicted you.