It still matters because of mental anchoring. In their mind they are being very generous by giving you 20% more than you make so their offer will be the minimum.

If they don’t know what you’re making now, they will think the minimum might be too little and if they really like you they will go higher than the 1.2x.

What if they were willing to offer 1.5x and you suggested, and ended up with, 1.2x because you were the first to provide a number?

That's the risk of going first.

They might be willing to offer 1.4x. If you tell them you want at least 1.2x, they're probably not doing 1.4x. If you ask them what the range is and they tell you a range, you can at least ask them for the top of the range or more. Worst case they just say they can't do X but can do Y, and then you have more info to negotiate with. Way better than not knowing and leaving money on the table.