The problem, I believe, is that the generic stylus devices you can buy are simply more for emulating a finger rather than actual tasks that a true stylus would be used for. A true stylus is like what the Samsung Note series devices have, or the top-end Galaxy Tab devices (Tab S3, Tab S4, etc) for that matter. The problem is that those devices are designed with the stylus in mind and have an extra Wacom layer built into the display for sensing the touch (or they used to) of the stylus, giving a more accurate result. Devices not designed for those specific styli (plural stylus, trust me) won't work with them.