no

Depends on the title I guess. Commercial games can also be one man games that lack a (proper) artist or the money/friends to make art and need to find another way to get something they can use. Free sites or cheap asset bundles are mostly the way to go with that. Sometimes the assets also simply get adjusted in a way it isn't that recognizable anymore.

Generally though, the bigger the studio (that being, having the proper artists) or more money, the less likely you will find free assets in a game. It's a matter of different factors though, but mostly depends on the one making the art being capable of delivering everything needed for the project.

AAA games are very likely to not have free assets. They have skilled people working on the specific needs of the game and simply don't need direct use of free assets, however it isn't uncommon that free assets are used as a reference should it be of use. Although, reference can be anything and is not limited to free assets. Re-using assets from previous games isn't that uncommon though.

I'd agree with the above -- purchased stock assets (which can often be quite cheap) are fairly common in hobbyist or indie games, but I don't know of any really prominent examples of commercially successful games using free assets.

That being said, if you're able to locate high quality free assets that are a good match for your game, and you're also able to produce a fun, high quality games, and then you're also able to market it well, there's no real reason you couldn't be the first such example -- the cases of popular games using stock assets (which by definition are not exclusive to that title) prove that you don't necessarily need unique assets to be successful.

Note also that there are some games that have been very successful commercially with extremely simple graphics that were created specifically for that games -- there's no reason these games would necessarily have been less successful using freely available assets that weren't created specifically. (Examples: Desktop Tower Defence, Fantastic Contraption).

//EDIT: When looking for the examples of simple graphics above I found an example of a very successful game that reportedly used creative commons assets: Crayon Physics - note that it has pretty minimal art at all however.

I think Realm of the Mad God used a few sprite packs for most of the main stuff (characters, items, etc).

I think Realm of the Mad God used a few sprite packs for most of the main stuff (characters, items, etc).

Specifically, it used Oryx's LOFI Fantasy sprites that were made for the Assemblee game jam in 2009. Realm of the Mad God was prototyped as part of that same game jam. Hence the reason why the biggest bad in RotMG is called Oryx.

Since then, that first sprite pack has been used in a bunch of games, and Oryx has also held a game jam specifically using his later sprite packs: http://oryxdesignlab.com/trials