Just as a nit, "font-size:10pt" is a lot worse than <font size="2"> from an accessibility perspective. <font size="2"> is "one notch below the user's default size". If the user sets a 20pt font, it's going to be larger than 10pt.
You could use "font-size: small" to get the size="2" behavior.
(Also, "font-family: Whatever", not "font-face: Whatever".)
Note that your CSS example is longer and requires combining two different syntaxes. And for one change, the difference in length and complexity is much more apparent.
> <span style="font-size: 10pt">Blah</span>
vs.
> <font size="2">Blah</font>
Which is easier to remember? Which is more obvious at a glance?
The former. The problem is just that you've learned what the latter means better than the former. I'm the opposite.
Plus, the former is an absolute value where the latter is not, as far as I've been able to tell. I know that first span will always be 10pt font. I have no idea what "2" even means in this context.
That may be true, but regardless of whether pt is a best practice, the point remains that it is still a unit. IMO that puts it ahead of the alternative example.