Yes. If sports does not happen in a vacuum then comparisons are unfair. If I go to the moon and break the record for long jumping should I be applauded?
Never thought I'd see the day ragebait made it to HN. Yes, let's pretend doing a long jump on the moon is comparable to running a marathon at its prescheduled time at its prescheduled location. Weather is always a factor in sports that take place outside. Might as well put asterisks on all accomplishments that took place on sunny days by your logic right?
Not sure I understand what you mean by "scientific." If you mean exactly reproducible, then almost nothing in athletics fits that definition. Every record in baseball, football, etc. would fail that definition.
There is no rule for marathons.