BHVR has little intention of closing the gap between solo and SWF because it benefits them

Solo survivor can be an excruciatingly unfun experience. It can arguably be said that on average SWF is stronger than killer, and killer is stronger than solo survivor. There are a few key things that can indicate BHVR has very little enthusiasm in changing this system, such as the fact they've claimed on a number of occasions to be looking into the solo/swf gap but never actually done anything about it in the months & years since apart from buff kindred a tiny bit, but the main problem is that it works better for them from a business perspective.

I can go on about how business decisions that lead to increased revenue (new characters to buy, new cosmetics, [THE RIFT PASS]) are immensely valued over ones that while nice for the players won't necessarily lead to raking in the dough (closing the gap, general balancing of characters/items/perks, fixing minor bugs, QoL improvements, implementing graphics settings), but that's a bit off topic and BHVR as a business does need to keep their employees employed. The fact they are a business selling you a product as a service is what needs to be kept in mind here.

You have an awful time as solo survivor. You play as killer and see how overwhelming SWF can be, with many of the perks at their disposal synergizing in ways that they never viably could as a solo player (OoO, For the People + Soul Guard, Breakout, Saboteur, anything massively buffed by having communication.) So you tell a few of your buddies "Hey there's this REALLY COOL game I found called Dead by Daylight, we should play together!" BHVR just made more sales and increased the odds of more in-game and DLC purchases occurring. The more purchases and playing, the higher the survivor population stays. Because for every killer you need 4x as many survivors to keep queue times to a minimum, this is doubly advantageous.

Now let's look at how the matchmaking works in order to "keep queue times low". You're matched with other survivors and a killer based off your MMR/Rank (let's pretend these actually work). Let's say the first killer you get dodges the lobby because he's an addonless Clown and just doesn't want to deal with this anymore tonight. So you get another killer, and maybe he dodges too. As BHVR themselves have stated, the longer you wait for a match, the more the search criteria is going to expand in both the ping of the other player(s), and the MMR/Rank of the other player(s). This means that if you're a high MMR/Rank SWF and killers dodge you because they don't want to deal with that, you are now much more likely than solo players to go up against even lower skilled killers that you can proceed to take a huge dump on.

So what happens if they make the efforts to close the gap? First of all there's a significant reallocation of resources for determining what exactly needs to be changed and how to implement it. Let's say they theoretically balance out the solo and SWF experience. They now need to do a pass of every killer and ensure the balance between the two roles is kept relatively even, as the only reason they have any appearance of doing so currently are the vast potential differences between the combined strength of a solo team vs. an SWF team. What is the financial incentive here when comparing it to the company's current trajectory?

I'd be very wary in disregarding this line of reasoning as conspiracy or simply chalking it up to BHVR's "laziness". While I think it would be silly to say any of this is done with a "malicious" intent as BHVR is a business that acts as a business does, there is a clear financial incentive in coaxing players along this path. The systems as they are both increases potential sales while allowing them to avoid relegating resources to tasks that won't net the same amount of revenue.