Retirement Accounts hierarchy: "Investments" top level account

[gnucash at gt500kr.fastmail.fm]

Hi,

For the last month I've been reading, reading and reading again about
how to operate Gnucash properly, more specifically the Tutorial and
Concepts Guide and this User list. Very interesting reading, for sure.
However the learning curve is steep even though I had been warned by
some Gnucash review articles I had read.

My question regards the treatment of retirement investments.

I've seen people using sub-accounts under the Assets top-level account
to track their retirement, more or less following the guidelines of
section "8.2. Setting Up Accounts" of the Tutorials and Concepts Guide.

However using the Account Hierarchy assistant within Gnucash, at the
2nd step I selected "Retirement Accounts" as well as the "Common
Accounts" and "Investments Accounts", and so I now have
Assets:Investments as well as a separate top level "Investments" and
Investments:Retirement . I've seen posts from users using the
Investments top-level account approach.

I've search for answers to that specific question, to no avail, so here
it is :
What's the purpose of having a separate top level account to hold
Investments, when there's already Assets:Investments ?

Thanks in advance

Pierre