What was the actual reason for removing sightstone / trackers?

Less vision = more people getting caught out = games ending quicker.

an item that nobody built will continue to not be built

oh dear

Im assuming it's the same reason they removed purchasable wards from the shop way back when. To make Pro matches more exciting to watch.

Not that I think that's a good thing.

Sightstone got merged with the support items so supports didnt have to feel like they had to sink 800 gold into their first item every single game and now it allows them to focus on buying other stuff first

tracker's knife was removed because it was pretty much mandatory in pro/high tier play and it ended up stalling games out and making laning phases longer because you had so much vision you could avoid early game ganks and made the junglers more or less farm bots