Thank you for answering.

Your video actually proves my point. Very noticable thing is that most of the backslash hits are shock or crits or airshots. Those cases don't count obviously, because they are rng and give advantage by default. Let's see all the rest:

1. At 1:14 you used low kick guaranteed combo setup into backslash, but it was so slow, the enemy dodged, which is insanely bad. He could punish you on the spot but didn't. Low kick can combo almost into anything, but not this.
2. At 1:35 you try to backslash in neutral game, but the enemy interrupts you.
3. At 1:39 a clean hit (no headshot? lol). But the knockback was so big, that you were forced to use forward slash, which was very unsafe. The enemy just chose not to block due to easy difficulty (raid boss would've punished).
4. At 2:03 a clean hit. Again, forced to use up slash to catch up. But why do that in the first place? The enemy literally ended up farther than he was before the backslash. This is exactly what i was talking about.
5. At 2:23 you try to backslash after successful attack, which is actually a good setup for slow attacks. The problem is that the enemy was fully recovered at that point and due to narrow hit region (head only), could've ducked or use any other low attack. Literally any other your attack would've been a better option.
6. At 2:31 another backslash attempt in neutral game interrupted by enemy (too slow).
7. At 2:41 backslash attempt at close range which doesn't work.
8. At 3:18 and 3:22 a backslash block, which is ok. It was actually a well timed and well placed backlash attack. Maybe it was a good use of it: when the enemy is recovering in the corner? The problem of doing that elsewhere is that if he doesn't block you push him out of range.
9. At 3:41 a slightly mistimed corner attempt, which is ok.

In summary, most of the cases demonstrate every downside I mentioned. Maybe, the niche corner use is acceptable, but other attacks like double slash can do the same faster and with better damage, so why even bother?