Bug type moves deal neutral damage to Grass/Poison types, so Fires still have that advantage, although personally I've not seen a grass type that's not Exeggutors in gyms in a long while. For me it's mostly just Vapes, Gyarados, Dragonite and Snorlax. Grasses don't place as highly in gyms since other top tier Pokemon got CP increases and on top of that they got reductions.
Also Snorlax doesn't have any super disadvantageous matchups. Snorlax is weak to fighting, but Fighting types have mediocre moves which negates that upside, enough that neutral attackers with STAB are more or less just as good, if not better.
It just depends on what people are using in your area, and what you have available to you. Not everyone has a Pinsir/Scyther to deal with Exeggutors.