Gchart is older/traditional SAS/Graph technology, whereas Sgplot is newer/different ODS Graphics technology (not part of the SAS/Graph product). They were developed separately, and they just do things 'differently'. That's the best explanation of "why" I can give you 🙂
As a work-around, perhaps you could tweak your SAS job to script out the html page, similar to what this person did in their sample code a few years ago ... except point to your svg instead of a gif. (you have to click the program/spoiler link, to see their code): https://communities.sas.com/t5/Graphics-Programming/Any-options-to-create-a-compressed-or-smaller-animated-GIF/td-p/663234
Something like this:
filename htmlout "spiral.html";
proc stream outfile=htmlout; BEGIN
<HTML><HEAD><TITLE>Animated spiral</TITLE></HEAD><BODY>
<IMG src='spiral.gif'>
</BODY></HTML>
;;;;
ods _all_ close;
... View more
