BotRK counter?
TL;DR: It's still being called the ADC for a reason.
I've been playing LoL for a very long time now and this item popped up one day and stuck around, despite having next to no counterplay from my perspective.
To clarify my opinion; the only strategy to countering this item is from the very start - before the game, through strategic champion selection. Which isn't a viable solution at a casual level of play and inhibits diversity. The only reasonable counter items to this once the game has started, are: Randuin's Omen, Frozen Heart, Thornmail. The problem is that BotRK is designed to counter them all!
(Worst Counter, Best Item) Randuin's Omen: bonus health vs. health shred, tanking-only AS reduction vs. AS boost, slow vs. slow+boost
(Best Counter, Niche Item) Frozen Heart: AoE AS reduction vs. AS boost
(Bad Counter, Bad Item) Thornmail: damage return vs. damage sustain
In individual match-ups, all of these counters to BotRK are countered by BotRK. Which is why building more of these 'counters' has a massively diminishing return in-game. The following biggest argument to counter BotRK, is armor. However, armor counters physical damage in general. Of course anyone building a health shredding BotRK is going to be shredding your armor as well! LW alone is enough to chunk armor stacking, without even factoring in runes/masteries/champion kit.
So, what strategies do you use to counter BotRK? Do you think BotRK needs a stronger counter? (a new item, rebalancing etc.)
I think BotRK needs a better counter because I think the only viable counter is a better pick during champion select. I think Riot should review and improve the interaction between BotRK and Thornmail. Thornmail doesn't return the damage of on-hit effects (AKA BotRK health shred). The return is also magic damage even though MR is WAY more accessible to a Marksman. Lastly, lifesteal (also built into BotRK) wrecks any damage output you might get out of Thornmail.
You know what should counter a healthier Thornmail-tank design in the future? Magic! (Not BotRK)