Gragas removed from League of Legends mid-tournament

This literally says absolutely nothing and makes no point. To record the game as a reproduction and not an encoded facsimile you have to have all previous pertinent information stored. The game does not produce a video encoded in any format because there is no video output. The game reproduces the match in question through a history of user commands as well as the notes of the build at the time, otherwise known as the details of the patch. The game definitely reproduces the play (this is known because you can produce glitches during replays), and to do so must retain previous build data. Otherwise, close kills' damages would not add up and you would see glitches in the health bar, among other things. These do not happen.
You could run replays offline in Source 1 using the console proving this info wasn't stored server side either.
There are even updated posts on DotA 2 blog about them changing the way that the replay system works from whatever it was, which I assume was standard to Source 1 if that's what you were referring to.
This is also evident in that heroes who have received a skill rework still have their old skills from pre-patch in an offline downloaded replay.
Seeing that the replays replicate previous patches (in that all the values are replaced as before and previous skill sets are restored), are not facsimile encoded/recorded, and are local, I don't understand where this dissension is coming from or how what you said even relates.
These replays are stored and produced server-side for Valve, so Riot would not even need to add much to the user client other than a menu to browse and download, and function to view them.
Maybe you missed the part where I said the patch from the time the replay was made was still maintained within the replay or old builds are stored locally?

 

VR medieval combat in Valiant looks ace