These attacks are not only feasible but are a recognized challenge within the community. The strategy involves miners submitting shares without producing valid blocks, thus harming the pool's overall success rate. There are different methods by which these attacks can be executed, including creating invalid templates for block withholding, which, despite being detectable through increased computational efforts by the pool, still presents a significant threat.

The detection of such attacks largely relies on statistical analysis, a tool equally effective against both sophisticated and more straightforward forms of block withholding. This underscores the inherent challenge pools face in safeguarding against these deceptive tactics. The effectiveness of any defense mechanism deployed by the pools, therefore, hinges on its ability to conduct thorough statistical analyses to identify anomalies indicative of withholding behavior.

Regarding Stratum V2's work selection process, integrating explicit negotiation mechanisms could potentially undermine its objective. The premise behind allowing miners the autonomy to select their work lies in bolstering Bitcoin's decentralization. If pools were to dictate the allocation of work, it would erode the very principle of decentralization that custom work selection seeks to preserve. Hence, the value added through decentralized pooling and custom work selection is contingent upon maintaining miners' freedom to mine preferred work, independent of pool directives. This autonomy not only reinforces the decentralized ethos of Bitcoin but also empowers miners to contribute more meaningfully to the network, whether they choose to mine within a pool or opt for solo mining when pool preferences do not align with their own.