esc = deselect

I think "all other softwares" is a bit of an overstatement. AFAIK:

• Maya: ⎈ Ctrl ⇧ Shift A or Esc
• 3DS Max: ⎈ Ctrl D or Esc
• zBrush: ⎈ Ctrl ⇧ Shift A
• Substance Painter: ⎈ Ctrl D
• Unreal Engine: ⎈ Ctrl ⇧ Shift A
• Unity: ⎈ Ctrl ⇧ Shift A
• Godot: ⎈ Ctrl ⇧ Shift A
• Photoshop: ⎈ Ctrl D
• Krita: ⎈ Ctrl ⇧ Shift A

If you wanted to align with other softwares, if anything it would be ⎈ Ctrl ⇧ Shift A . Which is what the Industry Compatible Keymap does already and which you should definitely use if having shortcuts similar to other softwares is of higher priority to you.

Meanwhile, in the default keymap: you can click any empty space to deselect, you can also press A if you set it to toggle the all-selection. If you didn't enable this, having ⎇ Alt / ⇧ Shift doing the opposite of the same shortcut without ⎇ Alt / ⇧ Shift is still a common pattern in different softwares, and that is including Blender, so selecting with A and deselecting with ⎇ Alt A makes sense here, even outside the Blender bubble.
Esc is already used to interupt any ongoing operator or task, I'm unsure it is wise to also make it deselect everything, especially considering that there are alternatives already available.

You can click the empty area in 3D viewport to deselect everything.

You can also just double-tap [a] to deselect everything. Reching up to esc feels pretty unnatural to me. You can already set this in the option if you like, though.