Microsoft DID NOT introduce online gaming. Steam came out a year later, so it was in the works when XBL was introduced. Not to mention, there was online gaming, just not over a unified network. Also, the original xbox didn't loosen sony's grip on the console market, sony was just stupid 7th gen.They had dominated the two previous gens making the two best selling home consoles of all time, so they were incredibly arrogant. Then they thought that people would still want a ps3 at a $600 price tag. Microsoft was able to capitalize off of this with the 360, until the ps3 became not stupid. Then the ps3 dominated the rest of the gen, putting a couple million ahead of the 360. Then you add in the fact that nintendo struck major gold with the wii and revitalized their consoles a bit.
Then this gen, nintendo made a console that appealed to very few people, creating another gamecube/n64 situation. Microsoft also came in incredibly arrogant (even though they still technically lost the 7th gen). They made a console that's weaker, bulkier, and more expensive. Which they just kind of fixed by making it the same price. Microsoft seems like sony at the beginning of last gen, except they don't have a reason to be arrogant. Unless something massive happens to change the tide, sony is reclaiming its thrown this gen.