How can HP block me from using a cheaper printer cartridge?

I was stopped from using a recycled toner product: it's going to cost me an extra 30%

I bought my usual recycled toner cartridge for my HP LaserJet printer. When I installed it I got a message telling me that printing was blocked as it was not an HP cartridge. It turns out that, in the last few weeks, HP has updated the printer firmware (without asking) to stop the use of non-HP cartridges. This means I will have to pay an extra 30% for my toner cartridges. What's going on?
PW, Argyll & Bute

I think I can answer that in a single word: profiteering. That's not how HP describes it. Altruism is the excuse it prefers. It tells me the practice it calls dynamic security" is to enhance the overall printing experience for our customers".