I think there are several reasons:
1 Sponsorship deals as Lightzy mentioned.
DHS has the whole Chinese team. I think it is unlikely they will sign or sponsor any euro players.
Not to mention about the financial support, this also leads to the second problem:
2 accessibility.
Blue sponge national H3 has limited supply on the open market. Without sponsorship, I am not sure how easy or difficult to order those direct from DHS for euro pro players. Not to mention the special customized version with more specified, accurate and consistent sponge hardness.
Pro players probably use 50-100 sheets every year.. How would you choose H3 if you don't have a confident supply.
3 user friendly / boosting
H3 is no better than tenergy / evolution or other non-tacky rubbers without boosting. I mean constant boosting like once or twice a month.
Lots of people don't like to reglue their racket every 2-4 weeks.
For young players also, euro coaches probably wouldn't recommend H3, as the coaches don't play H3. Why not just recommend a non-tacky tensor rubber which is better(than non-boosting H3) and less to care about (boosting) ?
If most young players in euro start their table tennis with non-tacky rubbers, they would probably keep using those. The technique they formed is with non-tacky rubbers.
Most Chinese young players start with H3, even without boosting. They used to that, the technique is for the H3.
The above discussed about why not many euro players use DHS or H3.
What about other tacky rubbers like K1 or spinart. Are they any good?
They are not as good as DHS. The sponge from DHS is unique, hard, supportive, especially good for tacky. Other brands tried tacky but still not as good.
It's like each brand's secret. Just like DHS tried to make a good non-tacky rubber(tinarc etc) or a tacky rubber which does not requiting boosting (H3-60) but never succeed....
Those are some of my thought.
btw, at leased Dimi tried H3 before.
https://www.tabletennisdaily.com/fo...arov-using-Hurricane-rubber-at-World-Cup-2016!