An ongoing business that intends to remain ongoing has to charge current customers based on the replacement cost of consumable items used to service those customers.

That's why for example gasoline prices react almost immediately after something affects (or even threatens to affect) the price of crude oil, even at gas stations that have just filled their storage tanks and will be selling that already purchases gas for quite a while.

Most of us don't usually thing of computer hardware as a consumable but to a hosting business it effectively is.

Because in a free market, making rational choices about pricing in line with the industry allows you to build capital to further expand, which coincidentally also lets you buy more RAM.

They will need to buy new hardware too I guess…

They are not raising prices for existing contracts, only new ones.