This is not true. You can replace the cpu easily on my brands of laptops. You just need to do your homework on what cpu you have in your computer, and realise that by doing so you will void your warranty, even if it is a cpu upgrade that is one of tge configurations your laptop comes with.
Some manufacturers go the route of apple, with BGA cpu's which are soldered on, but many laptop manufacturers still use sockets. (One motherboard tgen can support three or four different cpu) take for example my current Lenovo E440. It comes with a i5-4310m. When you ordered it you had a chance to upgrade the cpu to a i7-4712mq. Both of those cpu's are socket type cpus wuth the same 37w tdp. You can buy laptop cpu's from places like Aliexpress. Sure, ypu need to know what you're doing, but for certain laptops, if you do your homework, it is certainly possible.
...but homework is crucial.
derekullo :
You can't replace the cpu in a laptop.
At least not without advanced degrees in processor design and super expensive machinery powered by super expensive computers running super expensive software.
What is the intended use for this laptop?