Perhaps, like Nintendo, they learned the lessons from the collapse of the home video game market in 1983. When Nintendo was contemplating developing the NES, they took a deep look at what had caused the collapse. What they concluded was that the main cause of death was the market being flooded with too many crappy games.
Originally, if you wanted to write, say, an Intellivision game, you went and got a job with either Mattel or APh Technological Consulting (the company that did the hardware design, system software, and many of the early games for Mattel). If you wanted to do an Atari game, you went and got a job with Atari.
The games at this time were all pretty good. A consumer could go out, buy a game based just on the information printed on the box, and go home and be pretty sure they'd have a good experience.
As time went on, a few more companies joined the party. Activision and Imagic, for instance. These companies were started by people who had worked for Mattel or Atari or their contractors like APh, and generally produced quality games.
A consumer still could be confident that plunking down $40 or whatever for a new game, based just on the box description, would be a good move.
More time passed, and companies that had little or no connection to Atari and Mattel jumped in, using information gleaned by reverse engineering the consoles and system software. The information was not always complete, and they didn't know all the tricks and techniques we authorized developers knew to squeeze greatness out of the hardware. They produced a lot of crap games.
Consumers now found that spending $40 on a game was a big gamble. They had to work to get good games--be aware of brands, read reviews. They stopped buying--all games, not just the bad games.
Nintendo's conclusion was that their new console must be locked down. Only developers that Nintendo approved would be allowed to produce cartridges. This way, they could ensure that quality remained high, and get the now shy consumers to come back and give games another change.
It clearly worked--and consoles have been locked down ever since, and the console game market is huge.