[TYPO3-mvc] sense of recordType in Tx_Extbase_Domain_Model_FrontendUser?

[Thomas Hucke]

Hi all,
a new field 'tx_extbase_type' in fe_users has been introduced which 
obviously could be referenced in TS by entries like

    config.tx_extbase {
        persistence{
            enableAutomaticCacheClearing = 1
                updateReferenceIndex = 0
                    classes {
	        Tx_Extbase_Domain_Model_FrontendUser {
	            mapping {
	                tableName = fe_users
	                recordType = Tx_Extbase_Domain_Model_FrontendUser
	                    columns {
		        lockToDomain.mapOnProperty = lockToDomain
		    }

I'm looking into extbase and would like to make a 1:1 reference to the 
FrontendUser model.
After struggling with the storagePid now I ran into the issue that only 
FE-users will be selected by extbase that are configured in the BE to have 
"Tx_Extbase_Domain_Model_FrontendUser" as their Record Type.

I already was able to overcome this restriction by setting
    config.tx_extbase.persistence.classes.Tx_Extbase_Domain_Model_FrontendUser.mapping 
{
        tableName = fe_users
        recordType >
    }

Anyway I'd like to understand this and I would appreciate if anyone could 
explain the reasons to introduce this behaviour in extbase.