Theoretically, sure. My direct experience is that this rarely matters for reliability.
It can add latency, which is a valid reason to prefer a wired network, but I've almost never had problems with Wi-Fi reliability in the past couple of years that weren't caused by bugs in my Wi-Fi driver. I've more often had my uplink be unreliable than my Wi-Fi connection.
Reliability is a difficult thing to define. Sure, a Wi-Fi connection that's been established will probably not sporadically drop, and your mileage will probably be fairly consistent. But the moment you enter the realm of video games (which often transmit large bursts of data, requiring
both good throughput and latency), or high-resolution video streaming, you're starting to push the boundaries of what Wi-Fi can do in a residential setting.
in which case running cables inside the walls is likely a non-starter
I agree that running cables inside the wall would be ideal, and that it's a massive hassle, especially in rented accommodation. However, as a routine tenancy agreement violator, I can say with some confidence that landlords don't have the time to argue with you over a little bit of adhesive trunking attached to the walls, so long as you don't make it look like utter arse.
In an ideal world, every house would have an RJ45 port or two wired up with every electrical socket. In reality, a Wi-Fi repeater is often just as reliable as a wired connection (or at the very least, more reliable than the ISP it connects you to) and far simpler and more flexible to set up and maintain.
I've never found a Wi-Fi repeater that didn't suck, but I gave up on them early on. Or perhaps I was luckier with ISPs than you were. Wi-Fi repeaters don't make sense to me from a physics standpoint - you add congestion to an already noisy frequency, and now your device has to rely on *two* shitty radio connections. You've made the two biggest problems of Wi-Fi worse. I'd much rather go with powerline networking. It offers you a
chance of not ruining your bandwidth, generally provides good latency, and if mobility is a factor you can use them as a basis of a Wi-Fi access point.