Wrong. Depends on how you define your terms, and...
...you're obviously not defining them right.
To wit, for one thing: "[i]nfrastructure to support XML schema validation" obviously isn't such a trivial little thing as you seem to be trying to imply: None that the Critter has found yet is apparently capable of doing what he wants. Stands to reason that, if you define "[i]nfrastructure to support XML schema validation" as an XML schema-validator capable of enforcing relational integrity -- which, after all, is the operative requirement here -- then it'll be considerably LESS "lightweight" than whatever system you're referring to in your sweeping general claim that they are "somewhat easier to deploy".
For another, the reverse of the coin, you are just as obviously also trying to imply that "RDBMS infrastructure" MUST, of necessity, be some humongous monster... Newsflash from the Oracle consultant: As opposed to what far too many people (a group[*], BTW, you seem to be doing your best to declare yourself a part of) think, there ARE actually other RDBMSes than ours; many of them, in fact, so lightweight that I think it's not at all impossible to find an RDBMS that is "easier to deploy than" a relational-integrity-enforcing XML schema-validator.
Especially if you can't find ANY relational-integrity-enforcing XML schema-validator in the first place; then actually even Oracle would be "somewhat easier to deploy", wouldn't it...?
[*] That tricky class of users at the next step up from those absolute bottom-feeders who nod knowingly and say "Yeah, SQL, I've heard of it; it's a Microsoft database"; i.e, the guys who know just enough to be dangerous.
[link|mailto:MyUserId@MyISP.CountryCode|Christian R. Conrad]
(I live in Finland, and my e-mail in-box is at the Saunalahti company.)
Your lies are of Microsoftian Scale and boring to boot. Your 'depression' may be the closest you ever come to recognizing truth: you have no 'inferiority complex', you are inferior - and something inside you recognizes this. - [link|http://z.iwethey.org/forums/render/content/show?contentid=71575|Ashton Brown]