Spend a few minutes on Indiegogo and you'll come across a series of extraordinarily ambitious wearable devices promising to detect everything from your sleep patterns, to your stress levels, to the number of calories you've burned in the past hour. They've incited plenty of skepticism and the latest report from The Wall Street Journal shows why: the Apple Watch was initially intended as exactly that sort of multifunctional health-monitoring device, but the sensors available just weren't good enough. Heart activity, blood pressure, and stress levels were among the things Apple wanted to track with the Watch, however issues of complexity and reliability — such as getting accurate readings on users with hairy arms or dry skin — forced Apple into changing its plans.

That's not to say that the iPhone maker didn't try its hardest, with the WSJ's sources describing the four-year Watch project as a "black hole" that sucked in resources from elsewhere in the company. But in the end, not even the most advanced sensor technology that Apple could obtain or design was good enough to perform all those sophisticated health-monitoring functions. Additional regulatory hurdles could also arise if Apple were to try and interpret its data to suggest health advice, and all of these issues combined have compounded to produce the much more conventional Watch that is set to be released in April. Still, Apple appears confident that it will sell many Watches and has apparently ordered between five and six million units to be manufactured for the first three months of availability.

Features like measuring blood oxygen levels and blood pressure are said to only have been shelved at Apple, and subsequent iterations of its Watch are likely to progress closer to the original vision of a multifunctional health monitoring device. As of right now, the technology isn't advanced enough to match the ambition — not for Apple and even more certainly not for all those pie-in-the-sky Indiegogo ventures.