One problem with that is sometimes the estimates are done long before the work starts so when that item eventually gets to the top of the priority stack the person estimated for is working on something else instead. At this point things need to be re-estimated which can cause friction if the new estimate is longer (“but last time, you said…” or “when we asked Bob, he said…”).

What I've done in the past is give an estimate based on what a “standard” dev can be expected to do (everyone understands a junior is expected to be slower as they are new, that is why they are currently a junior and when they get up to speed they'll be promoted) with a comment on the ticket that the expected time will reduce by × if a named resource, or one of a group, is available to work on it. That way, medium term planning can be done on the basis of a “reasonable case” scenario and if the right people are available things will go better (and if there are multiple items in that state, short term planning will include deciding which ones being sped up, by using that person's time, confers most extra value).