You ask
Should wiki locks prevent voting?
In my personal opinion, no.
This is an oddity that has confused me for a while. Take, for example, some most excellent posts on Seasoned Advice:
These are important canonical posts there and if you note, have more people who have favorited them than have upvoted the question, likely because that's their only option and the (unlocked) answer votes also outnumber the question votes. There's even a note on the second one encouraging people to favorite it.
I'm sure that other sites have similar examples but these are the ones I'm most familiar with.
So... why is it like this? Let's talk about it a bit...
There's an iconic scene in Five Easy Pieces where Jack Nicholson tries to order a side of toast but the restaurant he and his friends are in doesn't offer side orders of toast, only English muffins or coffee rolls and the waitress won't budge because she doesn't make the rules... and it's not because they don't have wheat bread and the ability to toast it, it's just not on the menu. So he tries to get around it by ordering a chicken salad sandwich made with wheat toast without mayonnaise, butter, or lettuce... or chicken. It gets them kicked out of the restaurant.
Locks are kinda like that. We have four different lock reasons on our menu but they're really just three of the same menu item with a different name and description (post notice) and the fourth menu item (historical significance lock) is the first three plus cheese.

We have all of the individual ingredients but can only turn them on in a group, not one at a time. There is no à la carte menu and we don't take special orders.
As with Nicholson's attempt to order toast, you're asking for a very simple thing - a very reasonable and sensible thing, too - but the system isn't currently built to help with that. And, to be clear, it's not only Wiki locks that suffer from this. We have many outstanding requests in a variety of places for a comment-only lock going back to at least 2013 and comments about how awesome such a lock would be in the Teachers' Lounge generally attract many stars.
Locks were intended to prevent... essentially all behavior. Over time we realized that they could be useful to stop other things, too (comments, for example) but we were hard-coded into the specific behavior locks were built with and, rather than making more types of lock, we just created different explanations for the same lock in the form of the post notice - the current text of each appears in the screenshot above.
The lock prevents:
- comments
- voting (on that post)
- editing
- deletion
- closing/reopening (questions only)
- new answers (questions only)
In addition to this, Historical significance locks remove voting arrows and lock all of the answers in addition to the question. For more info, see the relatively newly minted Lock Help Center article.
So, you're asking for a chicken salad sandwich, minus the chicken salad, mayo, butter, and lettuce... but I'm not going to kick you out of Stack Exchange for asking for it.
I don't know when we'll be able to rework the lock system or what it will look like but it's definitely something that needs to be fixed and something I hope will be sooner rather than later. hairboat hinted at this in her answer to this related request when she said:
As for the other bits, we've kicked off some research about what breaking up the locking process might entail. Creating a lock buffet, if you will. No timeline on that but it's being explored;
What we end up with will probably end up somewhere between what we have now and what that question is asking for but getting there is going to take a good deal of work since we'd be starting from scratch and likely wanting to categorize existing locks appropriately.
There's a long list of really awesome features we'd like to revisit/revamp/create and this is one of them... so thanks for bringing this up!