“Are Christians obligated to attend every meeting of the local church?”
The way you instinctively feel about this question will likely depend on the type of church you attend. Christians in a declining work that is still trying to run all the programs it did when the meetings were better attended often put pressure on one another to get more involved and to fill the empty shoes of the departed with any fresh body they can draft into service. On the other hand, a highly organized institutional church may be paying people to fill those roles, with the result that Christians can easily come and go from church as they please without feeling that their presence at any particular meeting makes much difference to anyone else.
Of course, the more important question is What does the Lord think?