Couldn't agree more. Basically your current employer should really pay you what the salary you would get somewhere else plus an additional markup for the internal knowledge which you have already acquired (you should put a value on that as well).
Also don't believe any line manager or anyone else here posting that this is not a good strategy, because remember, every line manager is only an employee as well and has a line manager as well and they want to get paid a fair salary as well, so they either will do the same or they will have 100% understanding for it and if they don't then you know that the company has no interest in paying you a fair market value for your contribution.
This is the free market, companies love to play the game when it comes to having people let go (like SoundCloud), when it comes to taxes and when it comes to profit distribution and growth, so they should also expect to play the same game when it comes to negotiating employee salaries.
Also don't believe any line manager or anyone else here posting that this is not a good strategy, because remember, every line manager is only an employee as well and has a line manager as well and they want to get paid a fair salary as well, so they either will do the same or they will have 100% understanding for it and if they don't then you know that the company has no interest in paying you a fair market value for your contribution.
This is the free market, companies love to play the game when it comes to having people let go (like SoundCloud), when it comes to taxes and when it comes to profit distribution and growth, so they should also expect to play the same game when it comes to negotiating employee salaries.