This is even less likely to be successful if you're just going to take pokemon who've been randomly mentioned (in this case Garchomp and Blissey) and put them on the team, thus completely ignoring the set of steps you outlined in your first post of the thread.
The reason people aren't taking this seriously is because no "best" team exists. You're getting annoyed at the people who are saying "no perfect team exists", no "team is unbeatable" etc, but you could just as easily swap "perfect" and "unbeatable" with "the best", and these people's arguments would in most cases remain true.
Firstly, the metagame is too diverse these days to have any chance of covering every major OU threat defensively. What if we make "the best" team, that maximizes winning and minimizes losses... but there's no room in it for a Gyarados counter. By adding one, we end up with a less impressive win/loss ratio. The choices here are to either make the team less effective overall by shoehorning in a way to stop Gyarados, or let Gyarados rape the team. Whichever option you take, the team is no longer "the best", because it had to draw some short straws. That's just an example of how you can't build a "best" team because something (most likely something OU) is going to give it serious issues regardless of what six pokes and what six movesets are chosen.
The second is that the metagame is too volatile to build a single "best" team, even if you would define it as a team capable of flexing to suit new environments. Whatever team we ultimately created, it would be entirely possible to build a team containing six Pokemon, possibly with their own tailor-made movesets, that counters the team we made. Which team is then "the best"? The team with the best win/loss ratio, or the team that beats the team with the best win/loss ratio? And then what if people make a counter to the counter team? As you can see, this is an infinite chain. As soon as a theoretically "best" team is made, counters will be made for it, counters for the counters, and it ends up with the "best" team being just like any other well-made team: Effective in the right hands, useless against certain teams and advantageous against others. We've got plenty of teams exactly like that in the RMT forum already.
Really, the people saying this is a hopeless endeavor aren't just being pessimistic; It is actually virtually impossible.