Sorry for asking this beginner question.

I've written DTDs so far and read about XML Schemas. I understand that
they are a replacement of the DTD fundamentally, and therefore allow
for the validation of an XML document.

My question really is:

Why do we need XML Schemas other than for validation of an XML
document? I am more interested in knowing if already available
"common" XML tools such as the MSXML parser, or DOM Level 3
implementations in today's browsers can do something like:

a) read an XML Schema;
b) then, read the XML document that is defined in the schema;
c) ?? magic ?? read some translation rules (an XSLT file?) that says,
for instance, that <xs:element name="foo" type="xs:string" /> 's value
must go to the column "bar" of this SQL Server database, etc., etc.

So, my question really is, can the available XML tools in the market
from major vendors read an XML Schema, and then not simply validate an
XML document but also read some translation rules from an XSLT file
and do the transformation without a developer having to write any
bespoke application on his part, if he just writes the XML, XSD and
XSLT sheet?