That’s because some other manufacturers are doing the handling of MIDI Clock wrong. The intention behind MIDI Clock is that it is constantly being sent. Even when the sequencer is stopped. Technically, MIDI Clock has nothing to do with starting or stopping sequencers. The MIDI transport commands Start/Stop/Continue are responsible for this.
There is a reason why Elektron devices allow you to switch both the clock and the transport commands on and off separately. If your other devices react incorrectly because of a constantly incoming MIDI clock, you need to complain to their manufacturers. Elektron does everything right when it comes to MIDI clock.
By the way, you can read all about this in the official MIDI specification of the MMA.