Staking/nominating: low amounts don't work

# Problem
SSIA - there have been a few reports like this where staking lower amounts for nominating doesn't seem to work.
* The maximum number of nominators that is set within the runtime (`staking.maxNominatorsCount` = `20,000`) doesn't appear to be exceeded (`staking.counterForNominators` is only at `316`)
* The users are nominating with smaller amounts, but above `staking.minimumActiveStake`

# Examples
(the user below is attempting to nominate with 3800 $JOY and has tried to nominate other validators many times)

* I think another 2-3 users have reported a similar problem over time

# Solution
* It seems that `nomination pools` are more ideal for smaller stake amounts for nomination in cases like these
* I guess it needs to be investigated (if it hasn't already) of why this is happening