Is there a way to query for a list of values belonging to a specific field in a queryset? For instance, if I wanted an array of all the titles belonging to a subset of entries that I wish to query. The way I know how to do this currently is like so:
  {% set titleList = [] %}
  {% articleQuery = craft.entries().section('articles') %}
  {% for article in articleQuery.all() %}
    {% set titleList = titleList|merge([article.title]) %}
  {% endfor %}

The other way I can think of to do this operation is with the map twig filter, but I'm wondering if there is a way to query for such a field-value list straight away and avoid spending computational time on iterations.
Yep! It's not super well documented, but there's a little information about it down in the Advanced Element Queries section of the docs. It would look something like:
  {% set titleList = craft.entries.section('articles').select('title').column() %}

One thing to note, if you're selecting a field value instead of the title, the select parameter will look something like select('field_fieldHandle')