Jason Miller is answering a long list of reader's questions. In one of them, he BRIEFLY addressed the LBRP. He said, "In 99.99999999% of the magic that has been taught on the planet, there is no analogy to the daily banishing fixation that pollutes Ceremonial Magic." I don't think he'd disagree if I said he said they are unnecessary.
In a way I agree with him. I don't formally banish when I work with the Helpful Deity. Though I do relax, meditate, focus and then work. In a way, this is banishing mundane thoughts etc from myself. So, it is somewhat comparable to an LBRP. Please note the phrase 'somewhat comparable' does not mean 'the same as'.
I think it is safe to say that Jason's opinion is that one runs the risk of pissing off various spirits one is ejecting from a given area. He may be right. I think I remember him saying that it is also robs one of many helpful interactions from spirits as you're constantly ejecting them from your sphere. If he didn't sat that, I am.
Those that think you can not attract the desired forces/power/energy you need to attract without doing a banishing prior to the working are likely incorrect.
Doing an LBRP based upon the fear of that 'something' may mess up the spell is wrong. Using the LBRP and its variants like LIRP of Fire to focus a rite is correct. Using it as one layer of protection magick is also correct. If you succeed in seriously calling large parts of four archangels, you'll do pretty well. If you get little slivers of your own misperceptions, it won't help at all.
However, assuming any of the above is the purpose of the LBRP or BRH and therefor doing them is 'pollution' is also incorrect.
The point of constant banishings is to mimic a process called Tzim Tzum:
Tzimzum describes the first step in the process by which God began the process of creation by withdrawing his own essence from an area, creating an area in which creation could begin.
Yes, this can be applied to all acts of ceremonial magick. However, the point of GD is to become self-creative. The constant banishings slowly aid the process of removing the accumulated junk that attaches to us that make us less pure. Those acts combined with initiations, meditations, proper attitudes, self-assessment etc are a very important of the personal alchemical work of the tradition.
That is not to say that they are a) necessary for all acts of magick or b) there are not other systems that help one on a spiritual path. I am merely saying that as part of the GD system, they are necessary to work within that system, in most cases.