"Take Mini-discs no one but sony could make them and the format died because of it."
Lots of manufacturers made the players.
I have perhaps 100 recordable minidiscs at home, mostly JVC, Maxell and TDK, all big names in the recordable media market. Yes, a few Sony ones too, as they were usually the cheapest I could get in 80 minute capacity.
I suspect what killed MD was a combination of two things, both of which happened just as MD would have been getting into it's stride as a worthy replacement for cassette tapes:
1. MP3 players got a whole lot better, especially when the first affordable hard-disk based units were released. Why carry a couple of dozen albums on MD when half your CD collection would fit on a unit about the same size as a portable MD player?
2. Recordable CD became affordable and accessible even to non-computer people. Why use a minidisc when you could record to a cheaper blank CD, and play it in most normal CD players too?
MD-Data had to compete against well-established "standards" of the time, like the Iomega Zip disks. I think Memory Stick bombed outside of Sony for much the same reason: it was trying to enter a market with plenty of established competition (CF, SD and it's many siblings, even SmartMedia at the time) and offered no advantage over them whatsoever.
Sorry, all rather off-topic I know. IGMC... :)