[RPG] Can you gain a proficiency bonus, without being proficient

As of 2019, the new Sage Advice Compendium clearly states that they don't interact.

These aren't allowed to work together on a single check.

Can the rogue’s Reliable Talent feature be used in conjunction with Remarkable Athlete or Jack of All Trades?

No. Each of these features has a precondition for its use; Reliable Talent activates when you make an ability check that uses your proficiency bonus, whereas the other two features activate when you make an ability check that doesn’t use your proficiency bonus. In other words, a check that qualifies for Reliable Talent doesn’t qualify for Remarkable Athlete or Jack of All Trades. And Remarkable Athlete and Jack of All Trades don’t work with each other, since you can add your proficiency bonus, or any portion thereof, only once to a roll.

An earlier Jeremy Crawford tweet restates this:

Making sure this is clear: these features work together on a character. They don't work together on the same ability check.

This is definitive, and contradicts earlier apparent rulings, i.e. from the 2017 SA compendium.

You cannot gain the bonus from both Jack of all Trades and Proficiency, they are mutually exclusive.

You're misunderstanding the way ability checks work. An ability check is:

To make an ability check, roll a d20 and add the relevant ability modifier. As with other d20 rolls, apply bonuses and penalties, and compare the total to the DC.

The number you have written on your character sheet is not your ability check. It merely represents the combination of your ability modifier and the bonuses and penalties that will generally apply when you make a check of that type.

So when you make a Deception check, you add the relevant ability modifier (Cha), then any bonuses or penalties that apply. If you're proficient in Deception, one of those bonuses is your proficiency bonus. However, the check now includes your proficiency bonus, to Jack of All Trades no longer applies.