Some airlines/aircraft don't have autoland capabilities.
With the weather below you need Cat II or better.
ILS Cat I is good until 550 m Runway Visual Range (in the below table noted as R06/xxxx or R24/xxxx for the respective runways)
According to these jepp plates i found EGPH only has up to Cat II with a minimum RVR of 300m.
As you can see below it dropped below even that for a time, so no one could land.
Cat III requires quite an expensive amount of lighting for the runways and taxiways, especially if you want to go down below 300m RVR.
ARCHIVED METAR OF: 20171221 // FROM: 13 TO: 18 UTC
AIRPORTS REQUESTED: EGPH
EGPH 211320Z 30002KT 9999 6000N VCFG NSC 07/05 Q1032
EGPH 211350Z VRB02KT 9000 1500N VCFG NSC 07/05 Q1031
EGPH 211420Z 36002KT 0500 R06/0500 FG NSC 05/05 Q1031
EGPH 211450Z 33001KT 0500 R06/0600 FG NSC 04/04 Q1031
EGPH 211520Z 36002KT 2000 0500E R24/0400 PRFG NSC 04/03 Q1031
EGPH 211550Z 34003KT 0350 R24/0275 FG NSC 04/03 Q1031
EGPH 211620Z 32001KT 0400 R24/0325 FG NSC 03/03 Q1031
EGPH 211650Z 23003KT 0500 R24/0800 FG NSC 03/03 Q1031
EGPH 211720Z 24003KT 0500 R24/0600 BCFG NSC 02/02 Q1031
EGPH 211750Z 25002KT 0500 R24/0550 BCFG NSC 03/03 Q1032
EGPH 211820Z VRB03KT 0500 R06/1300 FG NSC 02/02 Q1032
EGPH 211850Z 24003KT 0400 R24/0350 FG VV/// 02/02 Q1032