Are multiple USB ports meant for attaching specific types of external devices?

As far as my knowledge and experience go, you do not need to connect a specific device to a specific USB port. The USB ports support a wide range of devices and accessories including but not limited to printers, scanners, external hard drives, smartphones and many other peripheral devices or accessories. USB stands for Universal Serial Bus. The word Universal clearly implies the basic principle of the port.
Also the contention that a card reader needs to be connected to the same port every time holds no logical reasoning. Technically, you can connect any device to any port. But, if your ports have different standards like USB 2.0 and USB 3.0 - you may consider connecting your device to port of required standard to get optimal performance, though it is not compulsory.

USB ports are not device specific. Though the connectors for the device can be device specific but not the USB port themselves.

Only difference between USB ports is the standards (2 or 3) being supported by the device or the operating system in use. For example laptops made prior to 2007 support USB2.0.

Also every USB Port on the laptop or the desktop are given for the sake of adding additional ports to the hardware. Also service engineer is not correct in his assessment of using same USB port all the time.

There is no such restriction from the USB port or the card reader device. So you should ignore that service engineers advice.

You can use any USB port of your laptop to any USB device and there is no issue at all. I am surprised to know the fact that a Service Engineer or Technician have told you a wrong info on this. I have my laptop and have 3 USB ports in it where I am using USB device in different ports at different time and found no issue even after many years of using.

The another one is, I am using multi USB hub from one of the USB port where it gives no issue at all. The multi USB what I am using from one of the USB port of the laptop has four USB ports again which I am using it for USB Data Card dongle, Laptop USB mouse, Sound card and USB Cooling pad. Heavy usage of the USB ports from every ports since a long time and so far no issue at all.

There is no such conditions for inserting USB devices to a PC.
I think the service engineer meant that if you connect the USB Pendrive to a specific port that will be better.
Because, every USB port may or may not have equal transfer speed.
There will be a better USB Port than others which have better capable than other ports in transferring data, it may be upgraded USB 3.0 version or any other reason.

So, it's better to connect the device in such USB Ports to get full advantage.
You May familiar with the Windows Warning Message "USB Can Work Faster". It says there are better ports than the connected one and you can use that for better experience.