I think Flash lost because it shot itself in the foot, Firebug or not.
Flash was way beyond the web stack of that time in pretty much every aspect, and it would still have some advantages even today if it was still supported.
But Adobe completely dropped the ball. The plugin was a buggy mess, which regularly topped the charts in term of vulnerabilities and accessibility was pretty bad, all fixable problems they didn't fix. Adobe also didn't work with browser vendors and web standardization bodies to improve integration, instead relying on the already obsolete nsapi. Browsers kept nsapi support just for Flash, but as some point, enough is enough. I believe that with a bit more care from Adobe, Flash could have been part of the web standards, and I think it would have been better that what we have now.
I don't know much about Silverlight but it looks like a Flash knockoff that didn't fix any of the core issue Flash had.
i think the greatest thing we lost with flash is even non-technical people making something in an editor, hitting export, and getting a single small file that worked similarly enough to an image that it was trivial to just upload somewhere and have it be embedded there.
This. I hated flash sites, but it gave non-technical people a chance to be creative. Designers especially loved it, though they often used it for wrong purposes (web pages) too.
But good luck teaching them how to make that tetris clone in React nowadays...
Flash is a shining example of the concept, “Faster than Possible”.
When all of the vendors have a similar product, you chose based on feature set and cost (not all costs are monetary). When only one vendor has an interesting feature set, you need to ask yourself why, and it it’s too good to be true.
Flash was way beyond the web stack of that time in pretty much every aspect, and it would still have some advantages even today if it was still supported.
But Adobe completely dropped the ball. The plugin was a buggy mess, which regularly topped the charts in term of vulnerabilities and accessibility was pretty bad, all fixable problems they didn't fix. Adobe also didn't work with browser vendors and web standardization bodies to improve integration, instead relying on the already obsolete nsapi. Browsers kept nsapi support just for Flash, but as some point, enough is enough. I believe that with a bit more care from Adobe, Flash could have been part of the web standards, and I think it would have been better that what we have now.
I don't know much about Silverlight but it looks like a Flash knockoff that didn't fix any of the core issue Flash had.