This question came up in the Online 10-day Retreat Nov 3, 2020, guided by Delson Armstrong. Day 4 was part of a daily 30 -minute discussion on the suttas, the Dhamma talk and reflections.
Slightly edited to improve readability
When you have one-pointed concentration or one-pointed focus, you're actually suppressing the hindrances. So, you're also suppressing the mind's ability to see the hindrances. After you come out of that one- pointed focus or that one-pointed concentration, what one will notice is that, for a period of time, it may seem all well and fine. But then the hindrances arise with a vengeance, and there are still those hindrances present.
Whereas, if you're using an open awareness in the case of the TWIM practice, using attention rooted in reality, and using this open Mindfulness you are already able to see how the hindrances are arising. And able to deal with them with Mindfulness, and then therefore activate the other enlightenment Factors.
In the case of the one-pointed focus or one-pointed concentration, none of those Factors are even present. There may be, sometimes, joy arising because of that one-pointed focus, but that is the wrong kind of joy. You can say it's ineffective joy, it's not necessarily the same Joy that you see with the enlightenment Factors. The mind may seem like it's collected, but it's not collected; it's suppressed, rather than collected.
Collected mind and unification of mind, or unified mindset, is an attention around the object of meditation - or the vehicle of meditation, as it's sometimes called - and so when you're around it, you have a more clear and open awareness to which you can now recognize when hindrances might arise. And when they do, you can quickly 6R them. Or when insights arise, like insights into the Three Characteristics of Existence, insights into the links of Dependent Origination, insights into the Four Noble Truths, and so on. This is the way that the Path would be most effective.