When building my PC, I got a PCI WiFi card but it turns out there was also a direct WiFi network interface built into the motherboard somehow
But I don't the GP comment was talking about that; I have also used WiFi without an antenna (PCB or otherwise), and it was also slow for me.
A dummy load is probably the best idea: an impedance mismatch would obliterate any chance of anything working (including Bluetooth fwiw).
If you know what you are doing and have explicitly disconnected/cut all antennas including entire MIMO arrays (many people miss one or more antennas) in the motherboard then the only remaining explanation is "accidental antennas".
This is only possible if the WiFi-chip has dangling metal pins/traces/joints whose length is comparable to that of its wavelength, in which case these will act as makeshift antennas. These will pickup ambient WiFi RF, but for this to work at all you need lots of RF power i.e. a very strong signal strength which means you have to be very close to the WiFi router.
The whole thing works because of Physics and not Engineering (the "accidental" part) and hence very iffy (may not work at all) and should not be relied upon.
That being said, without an antenna it is highly improbable that it could still find an open WiFi AP to connect to (especially if you don't have one in your house).
As an example - if you have a motherboard on your computer that supports wifi and comes with a port/plug for an antenna, you could remove that antenna and still receive a signal (IDK about sending) but it would suffer more signal loss due to the lack of antenna.
All that is just a guess of course. People more knowledgeable than me could explain/clarify.
Exactly the same way their PC did; re-read what they said.
I am not the person you asked the question of, but here is the answer;
Smart TVs have a built-in "WiFi-Chip" on the motherboard and its antenna hidden in the TV frame itself, exactly like the antennas in a Smartphone. The different radios on a Smart TV viz. OTA, WiFi, Bluetooth, Satellite, Zigbee etc. all operate at different frequency ranges and hence need their own antennas. Many of these antennas are either a) etched on the motherboard b) hidden within the plastic back frame or c) directly taped to it.
Axiom of RF Wireless - There can be no transmission/reception without an antenna either external or internal.
PS: Since RF Wireless is everywhere today and most people do not have much of an idea of this technology, i very highly recommend the book The Essential Guide to RF and Wireless by Carl Weisman for study. Expressly written for a non-technical audience, it explains everything simply and beautifully. It really gave me the invaluable overview and the grounding i needed to understand this important science/technology.