truncate is indeed a simplification.
For example the above technique can be condensed into:
{{ $caption := .Site.Params.caption | truncate 145 }}{{ $caption }}{{ end }}
However, truncate does not suit my needs.
truncate outputs: blahablah ...
meanwhile the technique with split above outputs: blahablah...
The space that is rendered between the last word and the ellipsis with truncate is undesirable for me
(I am aware that one could use regEx to eliminate that space, but that is a bit of an overkill).
It’s all a matter of style preference.