Urktheturt.
If you take 5 minutes out of your life to actually investigate standard raw 5e dnd, you will see that backgrounds come with a predetermined set of proficiencies they can give you, the player not having the choice to swap in whatever they want.
Indeed, most of them only have the 2 preset skills and no customization, and a few particular backgrounds let you make a choice of 1 or 2 off a list of like, 4 options.
The extent to which you are wrong when claiming standard raw 5e lets you take any two skills really just makes you look ridiculous.
At least take the one minute of your life neccessary to hop on DnDBeyond.com's character builder, which is built to match raw, and see that you can't do the customization you're claiming.
In any case, customized or not, a character having any given proficiency should be narratively justified, which means they absolutely should be dependent on the narrative implications of the chosen background.
I took 15 seconds out of my life to google "D&DBeyond Backgrounds"
https://www.dndbeyond.com/sources/basic-rules/personality-and-background#CustomizingaBackgroundYou might want to tweak some of the features of a background so it better fits your character or the campaign setting. To customize a background, you can replace one feature with any other one, choose any two skills, and choose a total of two tool proficiencies or languages from the sample backgrounds. You can either use the equipment package from your background or spend coin on gear as described in the Equipment section. (If you spend coin, you can’t also take the equipment package suggested for your class.) Finally, choose two personality traits, one ideal, one bond, and one flaw. If you can’t find a feature that matches your desired background, work with your DM to create one.
