What if Armor slowed your Movement speed?

Waiting for team builder to find a team, figured I'd post an idea that I had earlier on the boards, since I'm BORED ba dum tiss

Saw another fizz go full tank and today it made me laugh, just picturing doing all those back flips and dashes with all these heavy armors on. Can you imagine?

Been playing Witcher 3 when not playing League, and lighter armors are weaker but are for mobility and heavier are more durable, but slow you down.

JUST FOR FUN!, I wondered if league could benefit from having such a mechanic where defensive items slowed your MS by X%. Nothing too critical, just enough to deter from super-tanky-yet-still-super-mobile-one-shotting champs. Just enough to force you to decide between mobility or defense.

It becomes less thematic with Magic Resistance(magic shields are heavy?) so I'm not sure how that would work, maybe it doesn't need to be thematic because reasons of and . I'll edit OP if somebody suggest a good idea.

Again, this is just for fun. Don't take it too seriously.

Edit: Defensive items could get an individual weight assigned to them and would essentially act as a MS debuff. Weight's MS debuff would be factored into it's gold effeciency. Items like ohmwrecker would be lighter than items like Randuin's or Warmogs , and gold costs would increase/ decrease to reflect. Do I want less armor and still be mobile, or get the tankier item and sacrifice some mobility?