Nah, that rumor is 100% false.
Anyone with a multimeter can analyze the stock cable themselves. The 2.5mm plug on each channel of the stock H1707 cable are TRS plugs (tip, ring, sleeve). However, only the tip and sleeve are used (the tip is used for the + signal of each channel, and the sleeve is the ground). The center terminal (the ring) on the stock plugs are not used (ie they're not connected to anything; no tweeters, no nothing). This means that the stock plugs are in reality nothing more than mono (TS) plugs.
1More likely ran into the exact same parts sourcing issue I did for my mmcx adapters — the 2.5mm TRS plugs are more readily available (and thus cheaper) than 2.5mm TS (ie mono) plugs. The decision to use one in place of the other is strictly a cost/parts availability thing, and nothing more.
A TRS (stereo) plug can be used as a substitute for a TS (mono) plug. However, you cannot use a TS (mono) plus as a substitute for a TRS stereo plug.
I hope that clears up any confusion.