Walking Nexus needs to be removed from Nexus Siege

I've been playing a lot of Nexus Siege lately because it is the kind of mindless fun where I can play any champ in any role and I don't have to really worry about a meta because of how it is designed. In general I've been having a great time with it but whenever a game reaches 18 mins the most annoying forced ending comes in the way of the Walking Nexus. Whenever someone wins because the other team died at the unfortunate, awkward time of 18 mins it doesn't feel satisfying for either team really. The team that won doesn't feel like they won because they know it's all because the Nexus literally just walked itself to them and handed them the win even if they were losing like crazy, and the enemy team is obviously pissed off cause they died at just the wrong exact moment even if they had completely stomped the other team. Please stop trying to force us out of a match that could be fun for everyone by giving us an exact time that we need to finish the match. Nexus Siege is already a really fast paced game mode there is no need to cut off the how long you can have fun with it.