For me, as an SME user, I started using Ethernet when Dlink introduced
an ISA card [DE205] which had a 4-port hub built in (actually 5-port if
you counted the internal one), at not a great deal more than a normal
10Base-T card. I think it was about $250, when a typical desktop PC was
$2500.
[...]
Price was a major feature, but interoperability and backwards
compatibility were the tipping points.
Ah, yes, backwards compatibility: implementing the fantastic feature of
breaking the network... we all remember the fun of what happened when
someone incorrectly unhooked a 10base2 network segment; D-Link managed
to one-up that on the theoretically more-robust 10baseT/UTP by
introducing a card that'd break your network when you powered off the
attached PC.
Designer of that deserved to be whipped with some RG-58. 
... JG
In article <201004071023.o37ANtww018405@aurora.sol.net>, Joe Greco <jgreco@ns.sol.net> writes
interoperability and backwards compatibility were the tipping points.
Ah, yes, backwards compatibility: implementing the fantastic feature of
breaking the network...
By "backwards compatibility" I mean the ability to use the new LAN from a laptop that didn't have an Ethernet connection built in, and didn't have an optional [proprietary] internal Ethernet card available either.
Later on, of course, you would get PCMCIA cards and USB dongles rather than Centronics-port dongles. But the market for these remained dominated by the Ethernet standard, rather than others.
we all remember the fun of what happened when
someone incorrectly unhooked a 10base2 network segment; D-Link managed
to one-up that on the theoretically more-robust 10baseT/UTP by
introducing a card that'd break your network when you powered off the
attached PC.
That tale of woe doesn't really sound like it's the fault of backwards compatibility. Didn't the operational status of the LAX immigration department fall to zero for almost a whole day, once; as a result of a rogue network card crashing the LAN?