Currently blacklisting something for RedHat 7.4 only works so that you can say 'linux', 'rhel' or 'rhel-7.4'. If you know that something fails in all RHEL 7's, but not RHEL 8 or RHEL 6, you are left with the option of specifically listing all possible RHEL 7 distros there are or will be. I.e.

rhel-7.0
rhel-7.1
rhel-7.2
...
rhel-7.10

We should be able to just say any major version 7. Like this:

rhel-7.*

or with a partial match just

rhel-7

But the partial match is dangerous when we will have "rhel-70.1" in our hands (think in general here)