Beside the price point, they usually work and seem to provide reasonable accuracy.
So, if buying your first multimeter to measure some battery voltages and resistances, and if you were well informed about the dangers of using the multimeter improperly (especially in any non-voltage reading mode) prior to getting it, this might work well.
I think that obviously because of their price, they are popular around the world. Being a popular product, you're more likely to find repair and mod videos than for a less popular product. Maybe it's just the challenge/fun factor: "Let's see what I can do with this cheap meter". Modding it and failing is also less costly than modding an expensive meter and failing - so could be some type of learning experience depending on the mod (I haven't seen the mods).
Now, about the repair videos... these meters are not robust at all. Especially the probes (and on some models sockets) are likely to fail unless you add some support to the probes as soon as you get the meter. So, failing more frequently may be the cause of more repair videos, but likely the main reason is the same as the modding videos - it's a cheap and popular meter.