I disagree, unless we are discussing two different concepts of "grabbing."
The baseline way to apply nikkyo or sankyo or kotegaishe is to grasp uke's hand to secure it.
And people with bad arthritis need to find an alternate way to compensate for weak or painful grasp.
There are times to do standard nikkyo as nage hurts me way more than receiving it as uke
Might be a different use/definition of the word, "grab," maybe? There's grabbing like when you catch yourself on the handrail to avoid a fall, that's a seriously "grippy" grab, lock-down of the hands-fingers around something to attempt stasis, right?
Next one I can think of is climbing a rope, need a powerfully grippy-grab to do that.
Then there's the less-grippy grab when one goes up a ladder (the transfer from hand to hand for going up a ladder (unless frightened) is akin to walking, so more relaxed.)
Then there's an even less so for using a tool for, in decreasingly grippiness, simple to complex tools (i.e. screwdriver/hammer to... scalpel/artist's brush, perhaps).
Then there is the grab with no real grip at all to speak of, such as picking up a wine glass or the bloom of a flower. The hand needs to have a certain form and shape, but you don't grip the wine glass, you simply hold it.
It is at this end that I "try" (and do not always succeed, it is the real world out there) to "grab" my partner/opponent for wristy-bendy techniques, and the locking techniques. I'e found that I can do nearly everything without ever closing my hnd at all, using tagetana as Janet said, but I have to use both hands, or another part of my body, to secure the technique, where if I use just a bit of "grab" hand posture, I have the control I need.