Let's say you're a game designer making an MMORPG. The game just entered it's first stages of stable play.
You've introduced "Mega awesome obsidium gear", the best armor you can think of. But by doing this, you may have screwed up the game indefinitely. Why? You made the endgame items accessible before you actually have content between starting and getting all the good stuff.
This is a major problem. Let's now say that you want to put 40% more content into the game, and it takes you two months to do this. In those two months, the people who played the early-developed game will already be at endgame, giving them an unfair advantage. Once the game is finished, the hardest-to-get item will be in possesion of everyone who started playing the game earlier than anyone else.
This is unfair to the later players. This is a huge problem for independent developers, because it breaks the game. Why even play the game if you can just log online and buy the endgame gear since everyone already had it before the game became hard.
So this is one thing to look out for, don't make the highest leveled armor first.