Adapting the signal to Ethernet and Display methods is changing a hardware function, not unlocking additional software features.
Your link did not specify that dongles only unlock software features. Your link said that whilst dongles were initially used as anti-piracy devices or to unlock extra software features, the term has been generalised.
A dongle is a small piece of hardware that attaches to a computer, TV, or other electronic device in order to enable additional functions such as copy protection, audio, video, games, data, or other services. These services are available only when the dongle is attached.
Although the term "dongle" was originally used to refer only to software protection devices, it is now more broadly applied.
Furthermore, they give examples of dongles which attach to the USB as:
bluetooth
SD card readers
thumbdrives
So your contention is that based on the quote YOU provided
1. A bluetooth USB stick is a dongle
2. A USB thumbdrive is a dongle
3. A USB SD card reader is a dongle,
But,
1. A USB ethernet controller is not a dongle
2. A USB display port is not a dongle.
Riiiiight. That makes a whole lot of sense.
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IF we consider the Surface Pro 3 tablet then....
Your wrong on all those points. If you read the Surface Pro 3 thread on here, you will see some people do use it for programming, so it must do alright for that task considering it's more powerful processor, plus it can play some pretty demanding games, may not be the highest FPS and the settings need to be turned down but it will play them, plenty of You Tube videos show that. And web browsing will be the same on the Surface Pro as the MacBook.
The issue is that when the Surface Pro is good at all the things mentioned like programming or word processing, it IS being used in a laptop form, not as a tablet.