I recently watched a video on video game sales on Steam that would support that theory. Basically, you can roughly estimate your first year of sales by multiplying your first week of sales by 5.
See the video at about 10:20 for that particular detail:
So yeah, if your sales fall off so quickly after launch that in the first year you make only 5x as much as you made in the first week, then I can see why it would be so important to capture as much of those early sales as possible.
Also, this great article from 2001 about the copy protection methods built into Spyro 2 on PS1 mentions that this is one of their primary concerns. So at the very least we can say that this mindset about (or excuse for) DRM in video games is not a recent change.
This is what happened to Insomniac's 1999 Playstation release, Spyro 2: Ripto's Rage. Even though it had good copy protection, it was cracked in a little over a week. So when we moved on to Spyro: Year of the Dragon (YOTD), we decided that something more had to be done to try to reduce piracy. The effort was largely successful. Though a cracked version of YOTD has become available, it took over two months for the working patch to appear, after numerous false starts on the part of the pirates (the patch for the European version took another month on top of that). The release of patches that didn't work caused a great deal of confusion among casual pirates and plenty of wasted time and disks among the commercial ones.
Two months may not seem like a long time, but between 30 and 50 percent of most games' total sales occur in that time. Approximately 50 percent of the total sales of Spyro 2, up to December 2000, were in the first two months. Even games released in the middle of the year rather than the holiday season, such as Eidetic's Syphon Filter, make 30 percent of their total sales in the first two months. If YOTD follows the same trend, as it almost certainly will, those two to three months when pirated versions were unavailable must have reduced the overall level and impact of piracy. On top of this, since YOTD was released in Europe one month after the U.S., those two months protected early European sales from pirated copies of the U.S. version.-https://www.gamasutra.com/view/feature/131439/keeping_the_pirates_at_bay.php