The biggest thing to understand is that Veteran's do not currently have a way to even view their static "file" that is being reviewed. The VA and advocates with proper clearance can view both top-level and detailed information much more than the claimant themselves can. They basically get to logon to vets.gov to be told they are #10253 in line and it is currently at the "Processing Evidence" level and that's it.
Doesn't really make sense to have the claimant have to work so hard to know how to shape their own claim that they initiated. The easier the claimant can do the legwork, the less the government has to do to explain and pickup extra work (the government has certain obligations to fully assist).