I think it was largely that Dell and HP could enter the business market by selling units cheaper in bulk where Tiny only ever really existed in home computing. Most Tiny PC's were good for checking email and installing AOL bloatware up until the end of XP where vista and win 7 pushed people to buy new devices. By then it was too late for Tiny and Dell/HP had sold laptops and desktops to basically every school and business in the country even unseating IBMs dominance.

Its actually quite hard to find much info about Tiny online. The most i can find in a writeup is that "sales dropped" and that was about it.

Their PCs for general home computing lasted at least until the late XP and vista era. Our one saw 95, 98, ME and XP before it finally got replaced with a Dell.

Their kit was decent and partially upgradable which is why they saw quite a long lifespan. But Dell/HP took over pretty quickly releasing smaller and cheaper devices to schools and businesses which was a market Tiny never managed to enter afaik. Commercial areas were dominated by IBM devices at the time then switching to Dell/HP. The home market was never really that lucrative since home users rarely replace computers unlike businesses who throw them into landfill for fun.