It's pretty great to have a standard for templates to generate URIs, but it's equally important to parse URIs and extract the variables. It looks like this RFC skimps on that part:
In Section 1.4:
Some URI Templates can be used in reverse for the purpose of variable
matching: comparing the template to a fully formed URI in order to
extract the variable parts from that URI and assign them to the named
variables. Variable matching only works well if the template
expressions are delimited by the beginning or end of the URI or by
characters that cannot be part of the expansion, such as reserved
characters surrounding a simple string expression. In general,
regular expression languages are better suited for variable matching.