Question: Why are non-medical masks useful?

Answer passage (source: WHO):
page_title: Q&A on coronaviruses (COVID-19)
section_headers: Does WHO recommend wearing medical masks to prevent the spread of COVID-19?
section_content: Currently, there is not enough evidence for or against the use of masks
(medical or other) in healthy individuals in the wider community. However, WHO
is actively studying the rapidly evolving science on masks and continuously
updates its guidance.
Medical masks are recommended primarily in health care settings, but can
be considered in other circumstances (see below). Medical masks should be
combined with other key infection prevention and control measures such as hand
hygiene and physical distancing.
Healthcare workers
Why? Medical masks and respirators such as N95, FFP2 or equivalent are
recommended for and should be reserved for, healthcare workers while giving
care to patients. Close contact with people with suspected or confirmed
COVID-19 and their surrounding environment are the main routes of
transmission, which means healthcare workers are the most exposed.
People who are sick and exhibiting symptoms of COVID-19
Why? Anyone who is sick, with mild symptoms such as muscle aches, slight
cough, sore throat or fatigue, should isolate at home and use a medical mask
according to WHO’s recommendation on home care of patients with suspected
COVID-19. Coughing, sneezing or talking can generate droplets that cause can
spread the infection. These droplets can reach the face of others nearby and
land on the surrounding environment. If an infected person coughs, sneezes, or
talks while wearing a medical mask, this can help to protect those nearby from
infection. If a sick person needs to go to a health facility they should wear
a medical mask.
Anyone taking care of a person at home who is sick with COVID-19
Why? Those caring for individuals who are sick with COVID-19 should wear a
medical mask for protection. Again, close, frequent and prolonged contact with
someone with COVID-19 puts caretakers at high risk. National decision makers
may also choose to recommend medical mask use for certain individuals using a
risk-based approach. This approach takes into consideration the purpose of the
mask, risk of exposure and vulnerability of the wearer, the setting, the
feasibility of use and the types of masks to be considered.

Reviewer feedback on this answer:
They said that there is not enough evidence to say. It doesn't say why non-medical masks aren't recommended.
This response begins by quickly explaining that non-medical masks have not been proven to have benefits, then provides information about when medical masks should be worn. While this was not asked for as part of the question, it may be useful since after being told non-medical masks do not have proven benefits, a user is likely to wonder if they should wear a medical mask. (By the way, I think the consensus now is that non-medical masks DO help prevent asymptomatic carriers from spreading COVID-19 to others.)

Reviewer ratings:
Could be Improved
Acceptable

Answer passage (source: WHO):
page_title: Q&A: Infection prevention and control for health care workers caring for patients with suspected or confirmed COVID-19
section_headers: Can disposable medical face masks be sterilized and reused?
section_content: No. Disposable medical face masks are intended for a single use only. After
use they should be removed using appropriate techniques (i.e. do no touch the
front, remove by pulling the elastic ear straps or laces from behind) and
disposed of immediately in an infectious waste bin with a lid, followed by
hand hygiene.
Click here for more information on using masks in the context of the nCoV
outbreak.

Reviewer feedback on this answer:
The question asked was not a yes/no question, but this answer starts with "No". The content of the answer deals with reuse and disposal of medical face masks, but the question is about non-medical masks.
The question is about non-medical masks. The response talks about medical masks.

Reviewer ratings:
Bad
Bad

Answer passage (source: WHO):
page_title: Q&A: Masks and COVID-19
section_headers: What are non-medical masks and what is their use?
section_content: Non-medical masks are often homemade of breathable fabrics and can be
commercially available as well. There are numerous designs for fabric masks,
but they generally cover the nose and mouth, are secured with ties or elastic
loops, include multiple layers of fabric, and can sometimes be washed and re-
used.
The evidence about the benefits of these masks is limited. One good quality
study showed that the risk of respiratory infection is increased (and not
reduced) in health care workers using cotton cloth masks when compared to
medical masks. Cloth masks are currently being recommended by some countries
as a means of source control in the general population. Although their
protective effectiveness to the wearer is unknown, they may protect others if
the wearer is a pre-symptomatic or asymptomatic carrier.
WHO is continuing to gather and review data as new studies become available
and will update guidance accordingly.

Reviewer feedback on this answer:
It brought up a study on why non-medical masks might be helpful. It says that cloth masks are recommended.
The question asks why masks are useful, but the response first defines non-medical masks (someone who asked this question likely knows what a non-medical mask is) and then only vaguely addresses the question ("We don't know if masks are useful" is not the best answer to "Why are masks useful")

Reviewer ratings:
Excellent
Could be Improved