Some techniques and training do not stress the joints, others do. It depends on the martial art, the teacher and the kind of training. For example, a lot of judoka end up with bad knees. Likewise a lot of capoeira folks end up with back injuries.
Joint damage can be understood in 3 factors:
Too much stress, bad applied
If you try to do too much force or weight and at a bad angle, the joint can be destroyed. Anything that involves a lot of bodyweight moving fast - your own or someone else's is typically what produces it. Martial arts that use acrobatics, throws, or pivots on one foot tend to get these problems more. Obviously, training/sparring with joint locks with someone who lacks control and goes too hard also produces this, since locks are designed to overpressure joints when used combatively.
Long term damage happens when the joint is used improperly over years. This is usually where we see stuff like meniscus disc damage on one side of the knee vs. the other, calcium deposits in knuckles or wrists, or spinal disc bulges/slips.
This is particularly hard to screen for, as it requires a lot of knowledge of anatomy and kinesiology - it's not as simple as "some positions are bad for everyone" as much as "Oh, your knee happens to have grown in this particular angle so this stance needs to be modified by this much to be the kindest to your knee cartilage".
Because nearly every martial art trains repetitive movements to make certain actions automatic, this becomes a problem over time as you slowly grind away cartilage or over stretch certain stabilizing tendons. Very few teachers have this level of anatomical understanding - a standard movement that is correct for 70% or 80% of the population is usually what folks know and they will simply repeat it as "the correct way" for everyone...
Muscle stabilization and tendon strengthening
On the positive side, some training can improve your muscle stabilization and tendon strength to help protect tendons.
Assuming you have a technique that protects your joints, the next factors are things that involve strengthening stabilizers and having you use them in reaction to constantly changing erratic movements (balance exercises, sticky hands work) are useful. That is to say - the strength to absorb the stress has to be there, but also you have to train the body to be able to turn on the muscles in time to do so as well - otherwise the strength is useless if it's not there when you need it.
Tendon strengthening is done through light weight/resistance, repeated hundreds of times. Low stance work can help a lot in this regard for protecting the knees.