That is EXACTLY what happened. The criteria used to diagnose autism was expanded within the last 20 years, and so now if a kid has issues but they don't know what it is, they categorize it as autism.
Let me clarify -- the bolded section is absolutely not true. From your "linky":
Before the late 1980s and early 1990s, these children were diagnosed as retarded or having developmental delay, lead author William Barbaresi, a developmental paediatrician, told the BMJ.
Kid has issues and they don't know what it is? yeah, that is definitely not a kid who presents with characteristics such as MR or DD.
The diagnostic tools for diagnosing a child with autism has certainly been expanded to include pediatrician observations at an early age (the most optimal time to receive intense therapies to yield the best long term outcomes), however the criteria for diagnosis is most specific and isn't handed out like candy (or rather provided because the clinician is somehow unsure what the "issues" are, whatever the hell that means):
Diagnostic Criteria for 299.00 Autistic Disorder
[The following is from Diagnostic and Statistical Manual of Mental Disorders: DSM IV]
(I) A total of six (or more) items from (A), (B), and (C), with at least two from (A), and one each from (B) and (C)
(A) qualitative impairment in social interaction, as manifested by at least two of the following:
1. marked impairments in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body posture, and gestures to regulate social interaction
2. failure to develop peer relationships appropriate to developmental level
3. a lack of spontaneous seeking to share enjoyment, interests, or achievements with other people, (e.g., by a lack of showing, bringing, or pointing out objects of interest to other people)
4. lack of social or emotional reciprocity ( note: in the description, it gives the following as examples: not actively participating in simple social play or games, preferring solitary activities, or involving others in activities only as tools or "mechanical" aids )
(B) qualitative impairments in communication as manifested by at least one of the following:
1. delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime)
2. in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others
3. stereotyped and repetitive use of language or idiosyncratic language
4. lack of varied, spontaneous make-believe play or social imitative play appropriate to developmental level
(C) restricted repetitive and stereotyped patterns of behavior, interests and activities, as manifested by at least two of the following:
1. encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
2. apparently inflexible adherence to specific, nonfunctional routines or rituals
3. stereotyped and repetitive motor mannerisms (e.g hand or finger flapping or twisting, or complex whole-body movements)
4. persistent preoccupation with parts of objects
(II) Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years:
(A) social interaction
(B) language as used in social communication
(C) symbolic or imaginative play
(III) The disturbance is not better accounted for by Rett's Disorder or Childhood Disintegrative Disorder
http://www.autreat.com/dsm4-autism.html
